Implement Phase 8: Testing & Deployment

Testing Infrastructure:
- Configure Jest with Next.js integration and TypeScript support
- Add React Testing Library with proper setup for Next.js components
- Install and configure Playwright for E2E testing
- Create jest.setup.ts with mocks for Next.js router and browser APIs
- Add CSS module mocking with identity-obj-proxy

Unit Tests:
- Create LoadingFallback component tests covering all 5 variants
- Create tracking API tests for data transformation logic
- Test createActivity, getActivities data structure conversions
- Verify frontend (timestamp/data) to backend (startedAt/metadata) mapping

E2E Tests (Playwright):
- Create comprehensive tracking flow tests
- Test navigation to all tracker pages (feeding, sleep, diaper)
- Test homepage Today's Summary display
- Test AI Assistant and Analytics navigation
- Test feeding, sleep, and diaper tracker UI elements
- Configure multi-browser testing (Chrome, Firefox, Safari, Mobile)

CI/CD Pipeline (GitHub Actions):
- Create automated CI/CD workflow for master/main branches
- Run linting on every push and PR
- Execute unit tests with coverage reporting
- Run E2E tests (Chromium) in CI environment
- Build application and upload artifacts
- Upload test coverage to Codecov
- Upload Playwright test reports as artifacts

Test Scripts:
- npm test: Run Jest unit tests
- npm run test⌚ Run tests in watch mode
- npm run test:coverage: Generate coverage report
- npm run test:e2e: Run Playwright E2E tests
- npm run test:e2e:ui: Run E2E tests with UI mode
- npm run test:e2e:headed: Run E2E tests in headed mode

Documentation:
- Create comprehensive testing guide (tests/README.md)
- Document test structure and best practices
- Add troubleshooting section for common issues
- Include useful commands for debugging tests

Coverage Thresholds:
- Branches: 70%
- Functions: 70%
- Lines: 70%
- Statements: 70%

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

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

maternal-web/jest.setup.ts

@@ -0,0 +1,42 @@
+import '@testing-library/jest-dom'
+
+// Mock Next.js router
+jest.mock('next/navigation', () => ({
+  useRouter: () => ({
+    push: jest.fn(),
+    replace: jest.fn(),
+    prefetch: jest.fn(),
+    back: jest.fn(),
+    pathname: '/',
+    query: {},
+    asPath: '/',
+  }),
+  usePathname: () => '/',
+  useSearchParams: () => new URLSearchParams(),
+}))
+
+// Mock window.matchMedia
+Object.defineProperty(window, 'matchMedia', {
+  writable: true,
+  value: jest.fn().mockImplementation((query) => ({
+    matches: false,
+    media: query,
+    onchange: null,
+    addListener: jest.fn(),
+    removeListener: jest.fn(),
+    addEventListener: jest.fn(),
+    removeEventListener: jest.fn(),
+    dispatchEvent: jest.fn(),
+  })),
+})
+
+// Mock IntersectionObserver
+global.IntersectionObserver = class IntersectionObserver {
+  constructor() {}
+  disconnect() {}
+  observe() {}
+  takeRecords() {
+    return []
+  }
+  unobserve() {}
+}