Fix console warnings: remove SW registration, fix meta tag, clean manifest

- Remove service worker registration from footer (SW is already self-unregistering)
- Add mobile-web-app-capable meta to fix deprecation warning
- Remove missing icon references from manifest (only 192/512 PNGs exist)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

includes/footer.php

@@ -72,22 +72,7 @@
     </footer>
     
     <script src="/assets/js/main.js?v=<?= filemtime($_SERVER['DOCUMENT_ROOT'] . '/assets/js/main.js') ?>"></script>
-    
-    <!-- PWA Service Worker Registration -->
-    <script>
-        if ('serviceWorker' in navigator) {
-            window.addEventListener('load', () => {
-                navigator.serviceWorker.register('/sw.js')
-                    .then(registration => {
-                        console.log('SW registered:', registration.scope);
-                    })
-                    .catch(error => {
-                        console.log('SW registration failed:', error);
-                    });
-            });
-        }
-    </script>
-    
+
     <?php if (isset($extraScripts)) echo $extraScripts; ?>
 </body>
 </html>