Add Progressive Web App (PWA) support

[Copilot]

Enables installation of CloudMoon InPlay as a standalone app with offline support.

Changes

Manifest & Service Worker Routes

• Added /manifest.json route serving app metadata (name, theme, icons, display mode)
• Added /sw.js route serving service worker with network-first caching strategy
• Both dynamically generated from worker.js - no separate files needed

PWA Meta Tags

• theme-color, mobile-web-app-capable, apple-mobile-web-app-* for iOS/Android
• Manifest link and Apple touch icon

Service Worker Implementation

• Caches app shell on install (/, /manifest.json, /sw.js)
• Network-first fetch with cache fallback for offline support
• Explicit cross-origin request handling via fetch(event.request)
• Error handling on cache operations

Install Prompt

• Registers service worker on page load
• Captures beforeinstallprompt event with deferred prompt
• Shows toast notification when app is installable

// Service worker route in handleRequest()
if (url.pathname === '/sw.js') {
  return new Response(getServiceWorker(), {
    headers: { 
      'Content-Type': 'application/javascript',
      'Service-Worker-Allowed': '/'
    }
  });
}

Users can now install to home screen/desktop, launch in standalone mode, and access cached content offline.

Original prompt

make it so the site is also a PWA or web app

---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.