Implement comprehensive error handling

- Add try-catch blocks to all server actions with retry logic
- Implement exponential backoff retry mechanism for database operations
- Add input validation to all server actions
- Create ErrorBoundary component for React error handling
- Add page-level error handlers (error.tsx, global-error.tsx)
- Add route-specific error pages for list and item routes
- Enhance database connection with graceful error handling
- Add user-friendly error messages throughout the application
- Implement proper error logging for debugging

Task: 16. Implement error handling
Requirements: All (error handling is cross-cutting)

app/layout.tsx

@@ -3,6 +3,7 @@ import './globals.css'
 import ServiceWorkerRegistration from '@/components/ServiceWorkerRegistration'
 import OfflineIndicator from '@/components/OfflineIndicator'
 import { ToastProvider } from '@/components/ToastContainer'
+import ErrorBoundary from '@/components/ErrorBoundary'
 
 export const metadata: Metadata = {
   title: 'Ultimate Lists',
@@ -68,11 +69,13 @@ export default function RootLayout({
         <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
       </head>
       <body className="bg-gray-50 min-h-screen">
-        <ToastProvider>
-          <ServiceWorkerRegistration />
-          <OfflineIndicator />
-          {children}
-        </ToastProvider>
+        <ErrorBoundary>
+          <ToastProvider>
+            <ServiceWorkerRegistration />
+            <OfflineIndicator />
+            {children}
+          </ToastProvider>
+        </ErrorBoundary>
       </body>
     </html>
   )