feat: Set up PWA infrastructure with service worker, offline support, and manifest

- Created service worker (public/sw.js) with caching strategies
  - Cache-first strategy for static assets
  - Stale-while-revalidate for API responses and pages
  - Network-first fallback strategy
- Implemented offline fallback page (/offline)
- Updated manifest.json with complete PWA metadata
- Added service worker registration in app layout
- Created ServiceWorkerRegistration component for client-side registration
- Generated SVG icons for PWA (192x192 and 512x512)
- Added PWA meta tags for iOS Safari support

Validates Requirements: 4.1, 4.3, 4.4

.kiro/specs/ultimate-lists-app/tasks.md

@@ -151,7 +151,7 @@
 - [x] 10. Checkpoint - Ensure all tests pass
   - Ensure all tests pass, ask the user if questions arise.
 
-- [ ] 11. Set up PWA infrastructure
+- [x] 11. Set up PWA infrastructure
   - Create service worker (public/sw.js) with caching strategies
   - Implement cache-first strategy for static assets
   - Implement stale-while-revalidate for API responses