Implement professional error handling and user feedback system

Major UX Improvements:
- Replace all alert() dialogs with elegant toast notifications
- Add comprehensive loading states for all async operations
- Implement client-side form validation with visual feedback
- Add React Error Boundary for graceful error recovery

Components Added:
- Toast notification system with success/error/warning/info types
- useToast hook for easy notification management
- ErrorBoundary component with development error details
- Form validation with real-time feedback

User Experience:
- Professional toast notifications instead of browser alerts
- Loading indicators prevent double-clicks and show progress
- Immediate validation feedback prevents submission errors
- Graceful error recovery with retry options
- Enhanced accessibility with proper ARIA labels

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

components/ErrorBoundary.tsx

@@ -0,0 +1,76 @@
+'use client';
+
+import { Component, ErrorInfo, ReactNode } from 'react';
+
+interface Props {
+  children: ReactNode;
+  fallback?: ReactNode;
+}
+
+interface State {
+  hasError: boolean;
+  error?: Error;
+}
+
+export class ErrorBoundary extends Component<Props, State> {
+  public state: State = {
+    hasError: false,
+  };
+
+  public static getDerivedStateFromError(error: Error): State {
+    return { hasError: true, error };
+  }
+
+  public componentDidCatch(error: Error, errorInfo: ErrorInfo) {
+    console.error('ErrorBoundary caught an error:', error, errorInfo);
+  }
+
+  public render() {
+    if (this.state.hasError) {
+      if (this.props.fallback) {
+        return this.props.fallback;
+      }
+
+      return (
+        <div className="glass p-8 text-center max-w-md mx-auto mt-8">
+          <div className="text-6xl mb-4">⚠️</div>
+          <h2 className="text-xl font-semibold mb-4 text-red-400">
+            Something went wrong
+          </h2>
+          <p className="text-white/80 mb-6">
+            An unexpected error occurred. Please refresh the page or try again later.
+          </p>
+          <div className="button-group" style={{ justifyContent: 'center' }}>
+            <button
+              onClick={() => window.location.reload()}
+              className="btn btn-success"
+            >
+              <span className="icon">🔄</span>
+              Refresh Page
+            </button>
+            <button
+              onClick={() => this.setState({ hasError: false, error: undefined })}
+              className="btn-secondary"
+            >
+              <span className="icon">🔄</span>
+              Try Again
+            </button>
+          </div>
+          
+          {process.env.NODE_ENV === 'development' && this.state.error && (
+            <details className="mt-6 text-left">
+              <summary className="text-red-400 cursor-pointer font-mono text-sm">
+                Error Details (Development)
+              </summary>
+              <pre className="text-red-300 text-xs mt-2 p-3 bg-red-500/10 rounded border border-red-500/20 overflow-auto">
+                {this.state.error.stack}
+              </pre>
+            </details>
+          )}
+        </div>
+      );
+    }
+
+    return this.props.children;
+  }
+}