Add PWA support with service worker, web manifest, and notifications:

- Implement service worker (`sw.js`) for push notifications, caching, and periodic updates.
- Add web manifest (`manifest.webmanifest`) with PWA configuration and branding assets.
- Enhance live ban data integration with service worker for real-time summary updates.
- Register service worker and request notification permissions in `main.tsx`.
- Update branding assets to include additional sizes and formats (`favicon.png`, `pwa-maskable.png`, `screenshot-wide.svg`, `screenshot-mobile.svg`).
- Modify `LiveView` to send ban summaries to the service worker.