feat(docs): create sukr documentation site

Self-documenting docs site built with sukr itself (dogfooding):
- docs/site.toml with sukr.io base URL
- docs-specific templates with sidebar navigation
- Dark theme CSS, responsive layout
- Documentation: getting-started, configuration, features

Also: improved error chaining for better template debugging

docs/content/_index.md

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+---
+title: sukr
+description: Minimal static site compiler — suckless, Rust, zero JS
+---
+
+# Welcome to sukr
+
+**sukr** transforms Markdown into high-performance static HTML. No bloated runtimes, no client-side JavaScript, just clean output.
+
+## Why sukr?
+
+- **Fast builds** — Single Rust binary, parallel processing
+- **Zero JS** — Syntax highlighting at build time via Tree-sitter
+- **Flexible templates** — Runtime Tera templates, no recompilation
+- **Monorepo-ready** — Multiple sites via `-c` config flag
+
+## Quick Start
+
+```bash
+# Install
+cargo install sukr
+
+# Create site structure
+mkdir -p content templates static
+echo 'title = "My Site"' > site.toml
+echo 'author = "Me"' >> site.toml
+echo 'base_url = "https://example.com"' >> site.toml
+
+# Build
+sukr
+```
+
+## Documentation
+
+Browse the sidebar for detailed documentation on all features.

docs/content/configuration.md

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+---
+title: Configuration
+description: Complete reference for site.toml configuration
+weight: 2
+---
+
+# Configuration
+
+sukr is configured via `site.toml`. All settings have sensible defaults.
+
+## Basic Configuration
+
+```toml
+title    = "My Site"
+author   = "Your Name"
+base_url = "https://example.com"
+```
+
+| Field      | Required | Description                      |
+| ---------- | -------- | -------------------------------- |
+| `title`    | Yes      | Site title (used in page titles) |
+| `author`   | Yes      | Author name (used in feeds)      |
+| `base_url` | Yes      | Canonical URL for the site       |
+
+## Path Configuration
+
+All paths are optional. Default values shown:
+
+```toml
+[paths]
+content   = "content"    # Markdown source files
+output    = "public"     # Generated HTML output
+static    = "static"     # Static assets (copied as-is)
+templates = "templates"  # Tera template files
+```
+
+Paths are resolved **relative to the config file location**. This enables monorepo setups:
+
+```bash
+# Build site from subdirectory
+sukr -c sites/blog/site.toml
+# Paths resolve relative to sites/blog/
+```
+
+## CLI Options
+
+```bash
+sukr                           # Use ./site.toml
+sukr -c path/to/site.toml      # Custom config
+sukr --config path/to/site.toml
+sukr -h, --help                # Show help
+```
+
+## Frontmatter
+
+Each Markdown file can have YAML frontmatter:
+
+```yaml
+---
+title: Page Title
+description: Optional description
+date: 2024-01-15 # For blog posts
+weight: 10 # Sort order (lower = first)
+nav_label: Short Name # Override nav display
+section_type: blog # Override section template
+template: custom # Override page template
+---
+```
+
+### Section Types
+
+The `section_type` field determines which template is used for section indexes:
+
+- `blog` → `templates/section/blog.html`
+- `projects` → `templates/section/projects.html`
+- _(any other)_ → `templates/section/default.html`
+
+If not specified, sukr uses the directory name as the section type.

docs/content/features/_index.md

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+---
+title: Features
+description: Explore sukr's capabilities
+section_type: features
+weight: 3
+---
+
+sukr provides a focused set of features for building fast, minimal static sites.

docs/content/features/sections.md

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+---
+title: Sections
+description: Automatic section discovery and processing
+weight: 2
+---
+
+# Sections
+
+sukr automatically discovers sections from your content directory structure.
+
+## What is a Section?
+
+A section is any directory under `content/` that contains an `_index.md` file:
+
+```
+content/
+├── _index.md           # Homepage (not a section)
+├── about.md            # Standalone page
+├── blog/               # ← This is a section
+│   ├── _index.md       # Section index
+│   └── my-post.md      # Section content
+└── projects/           # ← This is also a section
+    ├── _index.md
+    └── project-a.md
+```
+
+## Section Discovery
+
+sukr automatically:
+
+1. Scans `content/` for directories with `_index.md`
+2. Collects all `.md` files in that directory (excluding `_index.md`)
+3. Renders the section index template with the items
+4. Renders individual content pages (for blog-type sections)
+
+## Section Types
+
+The section type determines which template is used. It's resolved in order:
+
+1. **Frontmatter override**: `section_type: blog` in `_index.md`
+2. **Directory name**: `content/blog/` → type `blog`
+
+### Built-in Section Types
+
+| Type       | Behavior                                               |
+| ---------- | ------------------------------------------------------ |
+| `blog`     | Sorts by date (newest first), renders individual posts |
+| `projects` | Sorts by weight, card-style listing                    |
+| _(other)_  | Sorts by weight, uses default template                 |
+
+## Section Frontmatter
+
+In `_index.md`:
+
+```yaml
+---
+title: My Blog
+description: Thoughts and tutorials
+section_type: blog # Optional, defaults to directory name
+weight: 1 # Nav order
+---
+```
+
+## Adding a New Section
+
+1. Create directory: `content/recipes/`
+2. Create index: `content/recipes/_index.md`
+3. Add content: `content/recipes/pasta.md`
+4. Optionally create template: `templates/section/recipes.html`
+
+That's it. sukr handles the rest.

docs/content/features/syntax-highlighting.md

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+---
+title: Syntax Highlighting
+description: Build-time code highlighting with Tree-sitter
+weight: 3
+---
+
+# Syntax Highlighting
+
+sukr highlights code blocks at build time using Tree-sitter. No client-side JavaScript required.
+
+## Usage
+
+Use fenced code blocks with a language identifier:
+
+````markdown
+```rust
+fn main() {
+    println!("Hello, world!");
+}
+```
+````
+
+## Supported Languages
+
+| Language   | Identifier            |
+| ---------- | --------------------- |
+| Rust       | `rust`, `rs`          |
+| Python     | `python`, `py`        |
+| JavaScript | `javascript`, `js`    |
+| TypeScript | `typescript`, `ts`    |
+| Go         | `go`, `golang`        |
+| Bash       | `bash`, `sh`, `shell` |
+| Nix        | `nix`                 |
+| TOML       | `toml`                |
+| YAML       | `yaml`, `yml`         |
+| JSON       | `json`                |
+| HTML       | `html`                |
+| CSS        | `css`                 |
+| Markdown   | `markdown`, `md`      |
+
+## How It Works
+
+1. During Markdown parsing, code blocks are intercepted
+2. Tree-sitter parses the code and generates a syntax tree
+3. Spans are generated with semantic CSS classes
+4. All work happens at build time
+
+## Styling
+
+Highlighted code uses semantic CSS classes:
+
+```css
+.keyword {
+  color: #ff79c6;
+}
+.string {
+  color: #f1fa8c;
+}
+.function {
+  color: #50fa7b;
+}
+.comment {
+  color: #6272a4;
+}
+.number {
+  color: #bd93f9;
+}
+```
+
+The exact classes depend on the language grammar.
+
+## Nix Language Support
+
+sukr includes full Nix highlighting with injection support. Bash code inside `buildPhase` and similar attributes is highlighted correctly:
+
+```nix
+stdenv.mkDerivation {
+  buildPhase = ''
+    echo "Building..."
+    make -j$NIX_BUILD_CORES
+  '';
+}
+```
+
+## Fallback
+
+Unknown languages fall back to plain `<code>` blocks without highlighting.

docs/content/features/templates.md

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+---
+title: Tera Templates
+description: Customizable templates without recompilation
+weight: 1
+---
+
+# Tera Templates
+
+sukr uses [Tera](https://tera.netlify.app/), a Jinja2-like templating engine. Templates are loaded at runtime, so you can modify them without recompiling sukr.
+
+## Template Directory Structure
+
+```
+templates/
+├── base.html               # Shared layout (required)
+├── page.html               # Standalone pages
+├── homepage.html           # Site homepage
+├── section/
+│   ├── default.html        # Fallback section index
+│   ├── blog.html           # Blog section index
+│   └── projects.html       # Projects section index
+└── content/
+    ├── default.html        # Fallback content page
+    └── post.html           # Blog post
+```
+
+## Template Inheritance
+
+All templates extend `base.html`:
+
+```html
+{% extends "base.html" %} {% block content %}
+<article>
+  <h1>{{ page.title }}</h1>
+  {{ content | safe }}
+</article>
+{% endblock content %}
+```
+
+## Available Context Variables
+
+### All Templates
+
+| Variable        | Description                     |
+| --------------- | ------------------------------- |
+| `config.title`  | Site title                      |
+| `config.author` | Site author                     |
+| `nav`           | Navigation items                |
+| `page_path`     | Current page path               |
+| `prefix`        | Relative path prefix for assets |
+| `base_url`      | Canonical base URL              |
+| `title`         | Current page title              |
+
+### Page Templates
+
+| Variable           | Description           |
+| ------------------ | --------------------- |
+| `page.title`       | Page title            |
+| `page.description` | Page description      |
+| `content`          | Rendered HTML content |
+
+### Section Templates
+
+| Variable              | Description                       |
+| --------------------- | --------------------------------- |
+| `section.title`       | Section title                     |
+| `section.description` | Section description               |
+| `items`               | Array of content items in section |
+
+### Content Item Fields (in `items`)
+
+| Variable           | Description         |
+| ------------------ | ------------------- |
+| `item.title`       | Content title       |
+| `item.description` | Content description |
+| `item.date`        | Publication date    |
+| `item.path`        | URL path            |
+| `item.slug`        | URL slug            |
+
+## Template Override
+
+Set `template` in frontmatter to use a custom template:
+
+```yaml
+---
+title: Special Page
+template: special
+---
+```
+
+This uses `templates/page/special.html` instead of the default.

docs/content/getting-started.md

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+---
+title: Getting Started
+description: Install sukr and build your first site
+weight: 1
+---
+
+# Getting Started
+
+This guide walks you through installing sukr and creating your first static site.
+
+## Installation
+
+### From source (recommended)
+
+```bash
+git clone https://github.com/nrdxp/sukr
+cd sukr
+cargo install --path .
+```
+
+### With Nix
+
+```bash
+nix build github:nrdxp/sukr
+./result/bin/sukr --help
+```
+
+## Create Your First Site
+
+### 1. Create directory structure
+
+```bash
+mkdir my-site && cd my-site
+mkdir -p content templates static
+```
+
+### 2. Create configuration
+
+Create `site.toml`:
+
+```toml
+title    = "My Site"
+author   = "Your Name"
+base_url = "https://example.com"
+```
+
+### 3. Create homepage
+
+Create `content/_index.md`:
+
+```markdown
+---
+title: Welcome
+description: My awesome site
+---
+
+# Hello, World!
+
+This is my site built with sukr.
+```
+
+### 4. Create templates
+
+Copy the default templates from the sukr repository, or create your own Tera templates.
+
+### 5. Build
+
+```bash
+sukr
+```
+
+Your site is now in `public/`.
+
+## Next Steps
+
+- Learn about [Configuration](configuration.html)
+- Explore [Features](features/index.html)

docs/site.toml

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+author   = "Sukr Contributors"
+base_url = "https://sukr.io"
+title    = "Sukr Documentation"
+
+[paths]
+content   = "content"
+output    = "public"
+static    = "static"
+templates = "templates"

docs/static/style.css

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+/* sukr docs — clean documentation theme */
+
+:root {
+  --bg: #0d1117;
+  --bg-sidebar: #161b22;
+  --fg: #c9d1d9;
+  --fg-muted: #8b949e;
+  --accent: #58a6ff;
+  --accent-hover: #79b8ff;
+  --border: #30363d;
+  --code-bg: #1f2428;
+  --success: #3fb950;
+}
+
+* {
+  margin: 0;
+  padding: 0;
+  box-sizing: border-box;
+}
+
+html {
+  font-size: 16px;
+  line-height: 1.6;
+}
+
+body {
+  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
+  background: var(--bg);
+  color: var(--fg);
+  display: grid;
+  grid-template-columns: 260px 1fr;
+  min-height: 100vh;
+}
+
+/* Sidebar */
+.sidebar {
+  background: var(--bg-sidebar);
+  border-right: 1px solid var(--border);
+  padding: 2rem 1.5rem;
+  position: sticky;
+  top: 0;
+  height: 100vh;
+  overflow-y: auto;
+}
+
+.sidebar header {
+  margin-bottom: 2rem;
+}
+
+.sidebar .logo {
+  font-size: 1.5rem;
+  font-weight: 700;
+  color: var(--accent);
+  text-decoration: none;
+  display: block;
+}
+
+.sidebar .tagline {
+  display: block;
+  font-size: 0.875rem;
+  color: var(--fg-muted);
+  margin-top: 0.25rem;
+}
+
+.sidebar nav {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+}
+
+.sidebar nav a {
+  color: var(--fg);
+  text-decoration: none;
+  padding: 0.5rem 0.75rem;
+  border-radius: 6px;
+  transition: background 0.15s, color 0.15s;
+}
+
+.sidebar nav a:hover {
+  background: var(--border);
+}
+
+.sidebar nav a.active {
+  background: var(--accent);
+  color: var(--bg);
+}
+
+/* Main content */
+main {
+  padding: 3rem 4rem;
+  max-width: 900px;
+}
+
+h1 {
+  font-size: 2.25rem;
+  margin-bottom: 1rem;
+  color: var(--fg);
+}
+
+h2 {
+  font-size: 1.5rem;
+  margin: 2rem 0 1rem;
+  padding-bottom: 0.5rem;
+  border-bottom: 1px solid var(--border);
+}
+
+h3 {
+  font-size: 1.25rem;
+  margin: 1.5rem 0 0.75rem;
+}
+
+p {
+  margin-bottom: 1rem;
+}
+
+.lead {
+  font-size: 1.125rem;
+  color: var(--fg-muted);
+  margin-bottom: 2rem;
+}
+
+a {
+  color: var(--accent);
+}
+
+a:hover {
+  color: var(--accent-hover);
+}
+
+/* Code */
+code {
+  font-family: ui-monospace, "Cascadia Code", "Source Code Pro", Menlo, monospace;
+  font-size: 0.875em;
+  background: var(--code-bg);
+  padding: 0.2em 0.4em;
+  border-radius: 4px;
+}
+
+pre {
+  background: var(--code-bg);
+  padding: 1rem;
+  border-radius: 8px;
+  overflow-x: auto;
+  margin: 1rem 0;
+  border: 1px solid var(--border);
+}
+
+pre code {
+  background: none;
+  padding: 0;
+}
+
+/* Section navigation */
+.section-nav {
+  display: flex;
+  flex-direction: column;
+  gap: 0.75rem;
+  margin-top: 1.5rem;
+}
+
+.section-link {
+  display: block;
+  padding: 1rem;
+  background: var(--bg-sidebar);
+  border: 1px solid var(--border);
+  border-radius: 8px;
+  text-decoration: none;
+  transition: border-color 0.15s;
+}
+
+.section-link:hover {
+  border-color: var(--accent);
+}
+
+.section-link strong {
+  display: block;
+  color: var(--fg);
+  margin-bottom: 0.25rem;
+}
+
+.section-link span {
+  font-size: 0.875rem;
+  color: var(--fg-muted);
+}
+
+/* Lists */
+ul, ol {
+  margin: 1rem 0;
+  padding-left: 1.5rem;
+}
+
+li {
+  margin-bottom: 0.5rem;
+}
+
+/* Tables */
+table {
+  width: 100%;
+  border-collapse: collapse;
+  margin: 1rem 0;
+}
+
+th, td {
+  padding: 0.75rem;
+  text-align: left;
+  border: 1px solid var(--border);
+}
+
+th {
+  background: var(--bg-sidebar);
+}
+
+/* Responsive */
+@media (max-width: 768px) {
+  body {
+    grid-template-columns: 1fr;
+  }
+  
+  .sidebar {
+    position: static;
+    height: auto;
+    border-right: none;
+    border-bottom: 1px solid var(--border);
+  }
+  
+  main {
+    padding: 2rem 1.5rem;
+  }
+}

docs/templates/base.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>{{ title }} | {{ config.title }}</title>
+    <link rel="canonical" href="{{ base_url }}{{ page_path }}" />
+    <link rel="stylesheet" href="{{ prefix }}/style.css" />
+  </head>
+
+  <body>
+    <aside class="sidebar">
+      <header>
+        <a href="{{ prefix }}/index.html" class="logo">sukr</a>
+        <span class="tagline">suckless static sites</span>
+      </header>
+      <nav>
+        {% for item in nav %}
+        <a
+          href="{{ prefix }}{{ item.path }}"
+          {%
+          if
+          page_path=""
+          ="item.path"
+          %}
+          class="active"
+          {%
+          endif
+          %}
+          >{{ item.label }}</a
+        >
+        {% endfor %}
+      </nav>
+    </aside>
+    <main>{% block content %}{% endblock content %}</main>
+  </body>
+</html>

docs/templates/content/default.html

@@ -0,0 +1,9 @@
+{% extends "base.html" %} {% block content %}
+<article class="doc-page">
+  <h1>{{ page.title }}</h1>
+  {% if page.description %}
+  <p class="lead">{{ page.description }}</p>
+  {% endif %}
+  <section class="content">{{ content | safe }}</section>
+</article>
+{% endblock content %}

docs/templates/homepage.html

@@ -0,0 +1,9 @@
+{% extends "base.html" %} {% block content %}
+<article class="homepage">
+  <h1>{{ page.title }}</h1>
+  {% if page.description %}
+  <p class="lead">{{ page.description }}</p>
+  {% endif %}
+  <section class="content">{{ content | safe }}</section>
+</article>
+{% endblock content %}

docs/templates/page.html

@@ -0,0 +1,9 @@
+{% extends "base.html" %} {% block content %}
+<article class="page">
+  <h1>{{ page.title }}</h1>
+  {% if page.description %}
+  <p class="lead">{{ page.description }}</p>
+  {% endif %}
+  <section class="content">{{ content | safe }}</section>
+</article>
+{% endblock content %}

docs/templates/section/default.html

@@ -0,0 +1,18 @@
+{% extends "base.html" %} {% block content %}
+<article class="section-index">
+  <h1>{{ section.title }}</h1>
+  {% if section.description %}
+  <p class="lead">{{ section.description }}</p>
+  {% endif %}
+  <nav class="section-nav">
+    {% for item in items %}
+    <a href="{{ prefix }}{{ item.path }}" class="section-link">
+      <strong>{{ item.frontmatter.title }}</strong>
+      {% if item.frontmatter.description %}
+      <span>{{ item.frontmatter.description }}</span>
+      {% endif %}
+    </a>
+    {% endfor %}
+  </nav>
+</article>
+{% endblock content %}

docs/templates/section/features.html

@@ -0,0 +1,18 @@
+{% extends "base.html" %} {% block content %}
+<article class="section-index">
+  <h1>{{ section.title }}</h1>
+  {% if section.description %}
+  <p class="lead">{{ section.description }}</p>
+  {% endif %}
+  <nav class="section-nav">
+    {% for item in items %}
+    <a href="{{ prefix }}{{ item.path }}" class="section-link">
+      <strong>{{ item.frontmatter.title }}</strong>
+      {% if item.frontmatter.description %}
+      <span>{{ item.frontmatter.description }}</span>
+      {% endif %}
+    </a>
+    {% endfor %}
+  </nav>
+</article>
+{% endblock content %}