Add comprehensive performance monitoring and testing infrastructure

- Implement performance dashboard with real-time metrics tracking
- Add React hooks for smart polling, debouncing, and active source lookup
- Create Jest testing framework with comprehensive test suites for components, API endpoints, and utilities
- Enhance UI components with optimized rendering and memoization
- Improve polling efficiency with visibility detection and adaptive intervals

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

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

components/__tests__/Toast.test.tsx

@@ -0,0 +1,203 @@
+import { render, screen, fireEvent, waitFor, act } from '@testing-library/react';
+import { ToastComponent, ToastContainer, Toast, ToastType } from '../Toast';
+
+// Mock timer functions
+jest.useFakeTimers();
+
+describe('ToastComponent', () => {
+  const mockOnRemove = jest.fn();
+  
+  const createToast = (type: ToastType = 'info', duration?: number): Toast => ({
+    id: 'test-toast',
+    type,
+    title: 'Test Title',
+    message: 'Test message',
+    duration,
+  });
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  afterEach(() => {
+    act(() => {
+      jest.runOnlyPendingTimers();
+    });
+    jest.useRealTimers();
+    jest.useFakeTimers();
+  });
+
+  it('renders toast with title and message', () => {
+    const toast = createToast();
+    render(<ToastComponent toast={toast} onRemove={mockOnRemove} />);
+    
+    expect(screen.getByText('Test Title')).toBeInTheDocument();
+    expect(screen.getByText('Test message')).toBeInTheDocument();
+  });
+
+  it('renders different types with correct styling', () => {
+    const types: ToastType[] = ['success', 'error', 'warning', 'info'];
+    
+    types.forEach((type) => {
+      const toast = createToast(type);
+      const { container } = render(<ToastComponent toast={toast} onRemove={mockOnRemove} />);
+      
+      const toastElement = container.firstChild as HTMLElement;
+      expect(toastElement).toHaveClass('glass');
+      
+      // Check for type-specific classes
+      const expectedClasses = {
+        success: 'bg-green-500/20',
+        error: 'bg-red-500/20', 
+        warning: 'bg-yellow-500/20',
+        info: 'bg-blue-500/20',
+      };
+      
+      expect(toastElement).toHaveClass(expectedClasses[type]);
+    });
+  });
+
+  it('shows correct icons for different types', () => {
+    const iconTests = [
+      { type: 'success' as ToastType, icon: '✅' },
+      { type: 'error' as ToastType, icon: '❌' },
+      { type: 'warning' as ToastType, icon: '⚠️' },
+      { type: 'info' as ToastType, icon: 'ℹ️' },
+    ];
+
+    iconTests.forEach(({ type, icon }) => {
+      const toast = createToast(type);
+      render(<ToastComponent toast={toast} onRemove={mockOnRemove} />);
+      
+      expect(screen.getByText(icon)).toBeInTheDocument();
+    });
+  });
+
+  it('calls onRemove when close button is clicked', () => {
+    const toast = createToast();
+    render(<ToastComponent toast={toast} onRemove={mockOnRemove} />);
+    
+    const closeButton = screen.getByLabelText('Close notification');
+    fireEvent.click(closeButton);
+    
+    // Should start the fade out animation
+    act(() => {
+      jest.advanceTimersByTime(300);
+    });
+    
+    expect(mockOnRemove).toHaveBeenCalledWith('test-toast');
+  });
+
+  it('auto-removes after default duration', () => {
+    const toast = createToast();
+    render(<ToastComponent toast={toast} onRemove={mockOnRemove} />);
+    
+    // Fast forward past the default duration (5000ms) plus fade out time (300ms)
+    act(() => {
+      jest.advanceTimersByTime(5300);
+    });
+    
+    expect(mockOnRemove).toHaveBeenCalledWith('test-toast');
+  });
+
+  it('auto-removes after custom duration', () => {
+    const toast = createToast('info', 2000);
+    render(<ToastComponent toast={toast} onRemove={mockOnRemove} />);
+    
+    // Fast forward past the custom duration (2000ms) plus fade out time (300ms)
+    act(() => {
+      jest.advanceTimersByTime(2300);
+    });
+    
+    expect(mockOnRemove).toHaveBeenCalledWith('test-toast');
+  });
+
+  it('error toasts stay longer than other types', () => {
+    const errorToast = createToast('error', 7000); // Explicitly set error duration
+    render(<ToastComponent toast={errorToast} onRemove={mockOnRemove} />);
+    
+    // Error toasts should have 7000ms duration by default
+    act(() => {
+      jest.advanceTimersByTime(6999);
+    });
+    expect(mockOnRemove).not.toHaveBeenCalled();
+    
+    act(() => {
+      jest.advanceTimersByTime(301); // 7000ms + 300ms fade out
+    });
+    expect(mockOnRemove).toHaveBeenCalledWith('test-toast');
+  });
+
+  it('renders without message when message is not provided', () => {
+    const toast: Toast = {
+      id: 'test-toast',
+      type: 'info',
+      title: 'Test Title',
+      // no message
+    };
+    
+    render(<ToastComponent toast={toast} onRemove={mockOnRemove} />);
+    
+    expect(screen.getByText('Test Title')).toBeInTheDocument();
+    expect(screen.queryByText('Test message')).not.toBeInTheDocument();
+  });
+});
+
+describe('ToastContainer', () => {
+  const mockOnRemove = jest.fn();
+  
+  const createToasts = (): Toast[] => [
+    {
+      id: 'toast-1',
+      type: 'success',
+      title: 'Success Toast',
+      message: 'Success message',
+    },
+    {
+      id: 'toast-2', 
+      type: 'error',
+      title: 'Error Toast',
+      message: 'Error message',
+    },
+  ];
+
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it('renders multiple toasts', () => {
+    const toasts = createToasts();
+    render(<ToastContainer toasts={toasts} onRemove={mockOnRemove} />);
+    
+    expect(screen.getByText('Success Toast')).toBeInTheDocument();
+    expect(screen.getByText('Error Toast')).toBeInTheDocument();
+  });
+
+  it('renders nothing when no toasts', () => {
+    const { container } = render(<ToastContainer toasts={[]} onRemove={mockOnRemove} />);
+    
+    expect(container.firstChild).toBeNull();
+  });
+
+  it('has proper positioning classes', () => {
+    const toasts = createToasts();
+    const { container } = render(<ToastContainer toasts={toasts} onRemove={mockOnRemove} />);
+    
+    const containerElement = container.firstChild as HTMLElement;
+    expect(containerElement).toHaveClass('fixed', 'top-4', 'right-4', 'z-50');
+  });
+
+  it('calls onRemove for individual toasts', () => {
+    const toasts = createToasts();
+    render(<ToastContainer toasts={toasts} onRemove={mockOnRemove} />);
+    
+    const closeButtons = screen.getAllByLabelText('Close notification');
+    fireEvent.click(closeButtons[0]);
+    
+    act(() => {
+      jest.advanceTimersByTime(300);
+    });
+    
+    expect(mockOnRemove).toHaveBeenCalledWith('toast-1');
+  });
+});