Implement modern sidebar navigation with hamburger menu

- Add responsive sidebar with hamburger toggle functionality
- Implement dual toggle buttons (inner/outer) for better UX
- Fix sidebar positioning to not overlap header and footer
- Add sticky footer with proper z-index layering
- Download and integrate Bootstrap source maps locally
- Optimize toggle icons: smaller, cleaner, no button styling
- Ensure sidebar respects footer boundaries
- Add smooth transitions and hover effects
- Fix active page highlighting and folder auto-expansion
- Create professional W3Schools-style navigation
- Maintain full offline capability with local assets

public/engine

@@ -0,0 +1 @@
+../engine

public/index.php

@@ -438,7 +438,7 @@ class CodePressCMS {
 }
 
 // Block direct access to content files
-$requestUri = $_SERVER['REQUEST_URI'];
+$requestUri = $_SERVER['REQUEST_URI'] ?? '';
 if (strpos($requestUri, '/content/') !== false) {
     http_response_code(403);
     echo '<h1>403 - Forbidden</h1><p>Direct access to content files is not allowed.</p>';

public/router.php

@@ -1,5 +1,5 @@
 <?php
-// Router file for PHP development server to handle security
+// Router file for PHP development server to handle security and static files
 
 $requestUri = $_SERVER['REQUEST_URI'];
 $parsedUrl = parse_url($requestUri);
@@ -23,9 +23,30 @@ foreach ($sensitiveFiles as $file) {
 }
 
 // Serve static files from engine/assets
-if (strpos($path, '/engine/') === 0 && file_exists(__DIR__ . $path)) {
-    return false; // Let PHP server serve the file
+if (strpos($path, '/engine/') === 0) {
+    $filePath = __DIR__ . $path;
+    if (file_exists($filePath)) {
+        // Set appropriate content type
+        $extension = strtolower(pathinfo($filePath, PATHINFO_EXTENSION));
+        $mimeTypes = [
+            'css' => 'text/css',
+            'js' => 'application/javascript',
+            'svg' => 'image/svg+xml',
+            'woff' => 'font/woff',
+            'woff2' => 'font/woff2',
+            'ttf' => 'font/ttf'
+        ];
+        
+        if (isset($mimeTypes[$extension])) {
+            header('Content-Type: ' . $mimeTypes[$extension]);
+        }
+        
+        // Serve the file
+        readfile($filePath);
+        return true;
+    }
 }
 
 // Route all other requests to index.php
-return false; // Let PHP server handle routing to index.php
+include __DIR__ . '/index.php';
+return true;