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)

components/ErrorBoundary.tsx

@@ -0,0 +1,81 @@
+'use client'
+
+import React, { Component, ReactNode } from 'react'
+import { AlertTriangle } from 'lucide-react'
+
+interface Props {
+  children: ReactNode
+  fallback?: ReactNode
+}
+
+interface State {
+  hasError: boolean
+  error: Error | null
+}
+
+export class ErrorBoundary extends Component<Props, State> {
+  constructor(props: Props) {
+    super(props)
+    this.state = { hasError: false, error: null }
+  }
+
+  static getDerivedStateFromError(error: Error): State {
+    return { hasError: true, error }
+  }
+
+  componentDidCatch(error: Error, errorInfo: React.ErrorInfo) {
+    console.error('Error caught by boundary:', error, errorInfo)
+  }
+
+  render() {
+    if (this.state.hasError) {
+      if (this.props.fallback) {
+        return this.props.fallback
+      }
+
+      return (
+        <div className="min-h-screen flex items-center justify-center p-4 bg-gray-50">
+          <div className="max-w-md w-full bg-white rounded-lg shadow-lg p-6 sm:p-8">
+            <div className="flex items-center justify-center w-12 h-12 sm:w-16 sm:h-16 bg-red-100 rounded-full mx-auto mb-4">
+              <AlertTriangle className="w-6 h-6 sm:w-8 sm:h-8 text-red-600" />
+            </div>
+            <h2 className="text-xl sm:text-2xl font-bold text-gray-900 text-center mb-2">
+              Something went wrong
+            </h2>
+            <p className="text-sm sm:text-base text-gray-600 text-center mb-6">
+              We encountered an unexpected error. Please try refreshing the page.
+            </p>
+            {this.state.error && (
+              <details className="mb-6 p-3 sm:p-4 bg-gray-50 rounded-lg text-xs sm:text-sm">
+                <summary className="cursor-pointer font-medium text-gray-700 mb-2">
+                  Error details
+                </summary>
+                <pre className="text-red-600 overflow-auto whitespace-pre-wrap break-words">
+                  {this.state.error.message}
+                </pre>
+              </details>
+            )}
+            <div className="flex flex-col sm:flex-row gap-3">
+              <button
+                onClick={() => window.location.reload()}
+                className="flex-1 px-4 py-3 bg-blue-500 hover:bg-blue-600 active:bg-blue-700 text-white rounded-lg transition-colors font-medium text-sm sm:text-base tap-target"
+              >
+                Refresh Page
+              </button>
+              <button
+                onClick={() => window.location.href = '/'}
+                className="flex-1 px-4 py-3 bg-gray-200 hover:bg-gray-300 active:bg-gray-400 text-gray-700 rounded-lg transition-colors font-medium text-sm sm:text-base tap-target"
+              >
+                Go Home
+              </button>
+            </div>
+          </div>
+        </div>
+      )
+    }
+
+    return this.props.children
+  }
+}
+
+export default ErrorBoundary