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/page.html

@@ -0,0 +1,6 @@
+{% extends "base.html" %} {% block content %}
+<article class="page">
+  <h1>{{ page.title }}</h1>
+  <section class="content">{{ content | safe }}</section>
+</article>
+{% endblock content %}