docs: Add /release-docs command, changelog page, and build instructions

- Add /release-docs command for regenerating documentation site
- Add commands/README.md with usage instructions for all commands
- Add changelog.html page rendering CHANGELOG.md in HTML format
- Add changelog CSS styles to docs.css
- Update navigation in all docs pages to include changelog link
- Fix command count from 16 to 13 in navigation
- Update CLAUDE.md with:
  - Documentation Site section explaining structure
  - /release-docs command in update checklist
  - Instructions for keeping docs up-to-date

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

plugins/compounding-engineering/docs/pages/commands.html

@@ -34,11 +34,17 @@
           <h3>Reference</h3>
           <ul>
             <li><a href="agents.html">Agents (24)</a></li>
-            <li><a href="commands.html" class="active">Commands (16)</a></li>
+            <li><a href="commands.html" class="active">Commands (13)</a></li>
             <li><a href="skills.html">Skills (11)</a></li>
             <li><a href="mcp-servers.html">MCP Servers (2)</a></li>
           </ul>
         </div>
+        <div class="nav-section">
+          <h3>Resources</h3>
+          <ul>
+            <li><a href="changelog.html">Changelog</a></li>
+          </ul>
+        </div>
         <div class="nav-section">
           <h3>On This Page</h3>
           <ul>