feat: transform library into Progressive Web App (PWA)

Implements issue #52 - adds complete PWA functionality with offline support, installability, and app-like experience.

PWA Features:
- Installable on mobile devices and desktop
- Offline support with smart caching strategies
- App-like experience with standalone display mode
- Full-screen mode and app icon on home screen
- Install prompt with beautiful banner UI

Manifest Configuration:
- Created manifest.json with app metadata
- App name: "Naomi's Library"
- Theme colour: #9d4edd (witchy purple!)
- Background colour: #1a1a2e (dark theme)
- Display mode: standalone (app-like)
- Icons: Multiple sizes specified (72-512px, maskable variants)
- Categories: entertainment, lifestyle

Service Worker Implementation:
- Cache-first strategy for static assets (JS, CSS, fonts, images)
- Network-first strategy for API requests with cache fallback
- Network-first strategy for HTML pages with cache fallback
- Cache versioning: library-v1 (static, dynamic, images)
- Automatic cache cleanup on activation
- Update checking every 60 seconds
- Message handling for cache clearing and skipWaiting

Offline Support:
- Created offline.html fallback page with beautiful UI
- Auto-retry when network comes back online
- Purple gradient matching app theme
- Informative messaging about offline state

Install Prompt:
- Created PwaInstallComponent with banner UI
- Detects installability and shows prompt
- "Install" and "Not Now" actions
- Responsive design for mobile and desktop
- Session storage for dismissal state
- Animated slide-up entrance

Services:
- PwaService: Manages service worker registration, install prompts, cache clearing
- Automatic initialization on app bootstrap
- Signals for reactivity: isInstallable, isInstalled, promptEvent
- Update detection and notification

HTML Updates:
- Added PWA meta tags (theme-color, description)
- Linked manifest.json
- Apple-specific meta tags for iOS support
- Apple touch icon specified

Build Configuration:
- Updated project.json to include PWA assets
- manifest.json, service-worker.js, offline.html copied to dist root

Integration:
- Added PwaService to app bootstrap
- Integrated PwaInstallComponent in main app template
- Install banner appears at bottom of screen
- Dismissible with session storage

Technical Notes:
- Service worker uses efficient caching strategies per resource type
- Handles Chrome extensions and non-HTTP protocols gracefully
- Supports message-based cache clearing
- Includes skipWaiting for immediate updates
- Compatible with iOS, Android, and desktop PWA standards

The library is now a fully-functional Progressive Web App that users can install on any device! The app works offline with cached content and provides an app-like experience with no browser UI in standalone mode.

Note: App icons still need to be generated/provided (placeholder paths specified in manifest).

✨ This feature was built by Hikari~ 🌸

apps/frontend/src/index.html

@@ -5,7 +5,14 @@
     <title>Naomi's Library</title>
     <base href="/" />
     <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <meta name="description" content="Naomi's curated collection of games, books, music, shows, manga, and art. Browse, engage, and suggest new additions!" />
+    <meta name="theme-color" content="#9d4edd" />
     <link rel="icon" type="image/x-icon" href="favicon.ico" />
+    <link rel="manifest" href="manifest.json" />
+    <link rel="apple-touch-icon" href="/assets/icons/icon-192x192.png" />
+    <meta name="apple-mobile-web-app-capable" content="yes" />
+    <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
+    <meta name="apple-mobile-web-app-title" content="Library" />
     <script defer src="https://analytics.nhcarrigan.com/js/pa-YUXAn1vhhRttySUAw_LMN.js"></script>
     <script>
       window.plausible=window.plausible||function(){(plausible.q=plausible.q||[]).push(arguments)},plausible.init=plausible.init||function(i){plausible.o=i||{}};