Fix #49: Add PWA support to make web-tail installable

[mishankov]

Summary

• Implemented Progressive Web App (PWA) functionality for the web interface
• App is now installable on mobile and desktop devices
• Added offline support via service worker
• Configured proper PWA manifest and icons

Changes

PWA Infrastructure

• Plugin: Integrated vite-plugin-pwa with Workbox for service worker generation
• Manifest: Created web manifest with app metadata (name, description, theme colors)
• Icons: Generated PWA-compliant icons:
  • pwa-192x192.png - Standard PWA icon
  • pwa-512x512.png - High-res PWA icon with maskable variant
  • apple-icon-180.png - Apple touch icon for iOS devices

Code Changes

• client/vite.config.ts: Configured VitePWA plugin with:
  • Service worker generation with auto-update
  • Workbox for precaching (15 static assets)
  • Manifest configuration with proper scope and start URL
  • Dev mode support for testing
• client/index.html: Added PWA meta tags:
  • Manifest link
  • Theme color
  • Apple touch icon link
  • Meta description
• client/src/main.ts: Added service worker registration:
  • Registers SW on app load
  • Handles offline ready and refresh events
  • Automatic updates

PWA Features

✅ Installability: Meets all PWA install criteria
✅ Offline Support: Service worker caches static assets
✅ Standalone Mode: Runs like a native app when installed
✅ Auto-updates: Service worker updates automatically
✅ iOS Support: Apple touch icon for iOS home screen

Build Integration

• Client build generates PWA assets (manifest, service worker, icons)
• Server embeds PWA-enabled frontend via Go embed
• All PWA files included in final distribution

Test plan

• Client build succeeds with PWA assets generated
• Server build succeeds with embedded PWA frontend
• Manifest.webmanifest created with correct metadata
• Service worker (sw.js) and Workbox generated
• Icons created in required sizes
• Manifest linked in HTML head
• No build errors or warnings

Testing in Browser

To test PWA installation:

1. Run cd client && bun run build
2. Run go run ./server from project root
3. Open http://localhost:4444 in Chrome/Edge
4. Look for install button in address bar
5. Install and verify standalone mode
6. Test offline functionality (disconnect network)

Closes #49

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