feat: add PWA support with service worker and update prompt

- Updated package.json to include vite-plugin-pwa and workbox-window.
- Added icon SVGs for PWA: icon-512.svg and maskable-512.svg.
- Created a manifest.json for PWA configuration.
- Implemented PwaUpdatePrompt component to notify users of available updates.
- Enhanced CookieConsent and SiteAssistant components for better layout and responsiveness.
- Updated global CSS for safe-area insets and mobile-first enhancements.
- Registered service worker in usePwaRegistration hook for managing updates.
- Modified Vite configuration to integrate PWA features and caching strategies.

frontend/package.json

@@ -48,6 +48,8 @@
     "tailwindcss": "^3.4.0",
     "typescript": "^5.5.0",
     "vite": "^5.4.0",
-    "vitest": "^4.0.18"
+    "vite-plugin-pwa": "^1.2.0",
+    "vitest": "^4.0.18",
+    "workbox-window": "^7.4.0"
   }
 }