feat(nav): add anchor TOC in sidebar for toc-enabled pages

- Pass extracted anchors through template context
- Render anchor links under active page when page.toc is true
- Hierarchical indentation by heading level (h2-h6)
- CSS styling: smaller font, muted color, border-left indicator
- Add toc: true to templates.md as example

src/main.rs

@@ -142,10 +142,16 @@ fn run(config_path: &Path) -> Result<()> {
         // Render individual content pages for all sections
         for item in &items {
             eprintln!("  processing: {}", item.slug);
-            let (html_body, _anchors) = render::markdown_to_html(&item.body);
+            let (html_body, anchors) = render::markdown_to_html(&item.body);
             let page_path = format!("/{}", item.output_path(&content_dir).display());
-            let html =
-                engine.render_content(item, &html_body, &page_path, &config, &manifest.nav)?;
+            let html = engine.render_content(
+                item,
+                &html_body,
+                &page_path,
+                &config,
+                &manifest.nav,
+                &anchors,
+            )?;
             write_output(&output_dir, &content_dir, item, html)?;
         }
 
@@ -259,9 +265,10 @@ fn process_pages(
             eprintln!("processing: {}", path.display());
 
             let content = Content::from_path(&path, ContentKind::Page)?;
-            let (html_body, _anchors) = render::markdown_to_html(&content.body);
+            let (html_body, anchors) = render::markdown_to_html(&content.body);
             let page_path = format!("/{}", content.output_path(content_dir).display());
-            let html = engine.render_page(&content, &html_body, &page_path, config, nav)?;
+            let html =
+                engine.render_page(&content, &html_body, &page_path, config, nav, &anchors)?;
 
             write_output(output_dir, content_dir, &content, html)?;
         }
@@ -278,13 +285,14 @@ fn generate_homepage(
 ) -> Result<()> {
     eprintln!("generating: homepage");
 
-    let (html_body, _anchors) = render::markdown_to_html(&manifest.homepage.body);
+    let (html_body, anchors) = render::markdown_to_html(&manifest.homepage.body);
     let html = engine.render_page(
         &manifest.homepage,
         &html_body,
         "/index.html",
         config,
         &manifest.nav,
+        &anchors,
     )?;
 
     let out_path = output_dir.join("index.html");

src/template_engine.rs

@@ -8,6 +8,7 @@ use tera::{Context, Tera};
 use crate::config::SiteConfig;
 use crate::content::{Content, NavItem};
 use crate::error::{Error, Result};
+use crate::render::Anchor;
 
 /// Runtime template engine wrapping Tera.
 pub struct TemplateEngine {
@@ -40,11 +41,13 @@ impl TemplateEngine {
         page_path: &str,
         config: &SiteConfig,
         nav: &[NavItem],
+        anchors: &[Anchor],
     ) -> Result<String> {
         let mut ctx = self.base_context(page_path, config, nav);
         ctx.insert("title", &content.frontmatter.title);
         ctx.insert("page", &FrontmatterContext::from(&content.frontmatter));
         ctx.insert("content", html_body);
+        ctx.insert("anchors", anchors);
         self.render("page.html", &ctx)
     }
 
@@ -56,6 +59,7 @@ impl TemplateEngine {
         page_path: &str,
         config: &SiteConfig,
         nav: &[NavItem],
+        anchors: &[Anchor],
     ) -> Result<String> {
         let template = content
             .frontmatter
@@ -66,6 +70,7 @@ impl TemplateEngine {
         ctx.insert("title", &content.frontmatter.title);
         ctx.insert("page", &FrontmatterContext::from(&content.frontmatter));
         ctx.insert("content", html_body);
+        ctx.insert("anchors", anchors);
         self.render(template, &ctx)
     }
 
@@ -145,6 +150,8 @@ pub struct FrontmatterContext {
     pub tags: Vec<String>,
     pub weight: Option<i64>,
     pub link_to: Option<String>,
+    /// Enable table of contents (anchor nav in sidebar)
+    pub toc: bool,
 }
 
 impl From<&crate::content::Frontmatter> for FrontmatterContext {
@@ -156,6 +163,7 @@ impl From<&crate::content::Frontmatter> for FrontmatterContext {
             tags: fm.tags.clone(),
             weight: fm.weight,
             link_to: fm.link_to.clone(),
+            toc: fm.toc.unwrap_or(false),
         }
     }
 }