feat: add projects page route and navigation link

- Add GET /projects route in server.js with authentication check
- Serve projects.html when authenticated, redirect to login otherwise
- Add navigation header to both landing page and projects page
- Include Sessions, Projects navigation links with active state styling
- Add logout button to navigation header
- Style navigation with dark theme matching existing design
- Make navigation responsive for mobile devices

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

server.js

@@ -89,6 +89,17 @@ app.get('/claude/ide/*', requireAuth, (req, res) => {
   res.sendFile(path.join(__dirname, 'public', 'claude-ide', 'index.html'));
 });
 
+// Projects page route
+app.get('/projects', (req, res) => {
+  if (req.session.userId) {
+    // Authenticated - serve projects page
+    res.sendFile(path.join(__dirname, 'public', 'projects.html'));
+  } else {
+    // Not authenticated - redirect to login
+    res.redirect('/claude/');
+  }
+});
+
 // Serve static files (must come after specific routes)
 app.use('/claude', express.static(path.join(__dirname, 'public')));