refactor: move personal site to sites/nrd.sh/

Reorganize for monorepo structure:
- Move content/, templates/, static/, site.toml → sites/nrd.sh/
- Frees root for sukr docs site
- Build with: sukr -c sites/nrd.sh/site.toml

sites/nrd.sh/templates/content/default.html

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