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

app/layout.tsx

@@ -1,12 +1,23 @@
 import type { Metadata } from 'next'
 import './globals.css'
+import ServiceWorkerRegistration from '@/components/ServiceWorkerRegistration'
 
 export const metadata: Metadata = {
   title: 'Ultimate Lists',
-  description: 'The ultimate todo list app',
+  description: 'The ultimate todo list app with advanced task management',
   manifest: '/manifest.json',
   themeColor: '#3B82F6',
   viewport: 'width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no',
+  appleWebApp: {
+    capable: true,
+    statusBarStyle: 'default',
+    title: 'Ultimate Lists',
+  },
+  applicationName: 'Ultimate Lists',
+  icons: {
+    icon: '/icon-192.svg',
+    apple: '/icon-192.svg',
+  },
 }
 
 export default function RootLayout({
@@ -16,7 +27,17 @@ export default function RootLayout({
 }) {
   return (
     <html lang="en">
-      <body className="bg-gray-50 min-h-screen">{children}</body>
+      <head>
+        <link rel="apple-touch-icon" href="/icon-192.svg" />
+        <meta name="apple-mobile-web-app-capable" content="yes" />
+        <meta name="apple-mobile-web-app-status-bar-style" content="default" />
+        <meta name="apple-mobile-web-app-title" content="Ultimate Lists" />
+        <meta name="mobile-web-app-capable" content="yes" />
+      </head>
+      <body className="bg-gray-50 min-h-screen">
+        <ServiceWorkerRegistration />
+        {children}
+      </body>
     </html>
   )
 }