feat: add projects showcase and Lux-powered static file server

- Add website/serve.lux: static file server using HttpServer effect
  - Demonstrates serving the Lux website with Lux itself
  - Handles index files, clean URLs, and 404 responses

- Add website/projects/index.html: example projects showcase
  - Features 6 real project cards (REST API, Todo App, JSON Parser, etc.)
  - Highlights Task Manager API demonstrating all 3 killer features
  - Links to full source code in the repository

- Update examples sidebar with Projects section

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

website/examples/index.html

@@ -194,6 +194,14 @@
                 <li><a href="middleware.html">Middleware</a></li>
                 <li><a href="routing.html">Routing</a></li>
             </ul>
+
+            <h2>Projects</h2>
+            <ul>
+                <li><a href="/projects/">All Projects</a></li>
+                <li><a href="/projects/#rest-api">REST API</a></li>
+                <li><a href="/projects/#todo-app">Todo App</a></li>
+                <li><a href="/projects/#json-parser">JSON Parser</a></li>
+            </ul>
         </aside>
 
         <div class="examples-content">