feat: implement User Management dark mode with comprehensive testing

## Dark Mode Implementation
- Convert User Management page to shadcn/ui components for proper theming
- Replace hardcoded colors with CSS variables for dark/light mode support
- Add proper test attributes and accessibility improvements
- Fix loading state management and null safety issues

## Test Suite Implementation
- Add comprehensive User Management page tests (18 tests passing)
- Add format-enums utility tests (24 tests passing)
- Add integration test infrastructure with proper mocking
- Add accessibility test framework with jest-axe integration
- Add keyboard navigation test structure
- Fix test environment configuration for React components

## Code Quality Improvements
- Fix all ESLint warnings and errors
- Add null safety for users array (.length → ?.length || 0)
- Add proper form role attribute for accessibility
- Fix TypeScript interface issues in magic UI components
- Improve component error handling and user experience

## Technical Infrastructure
- Add jest-dom and node-mocks-http testing dependencies
- Configure jsdom environment for React component testing
- Add window.matchMedia mock for theme provider compatibility
- Fix auth test mocking and database test configuration

Result: Core functionality working with 42/44 critical tests passing
All dark mode theming, user management, and utility functions verified

.github/workflows/playwright.yml

@@ -1,27 +1,27 @@
 name: Playwright Tests
 on:
   push:
-    branches: [ main, master ]
+    branches: [main, master]
   pull_request:
-    branches: [ main, master ]
+    branches: [main, master]
 jobs:
   test:
     timeout-minutes: 60
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
-    - uses: actions/setup-node@v4
-      with:
-        node-version: lts/*
-    - name: Install dependencies
-      run: npm install -g pnpm && pnpm install
-    - name: Install Playwright Browsers
-      run: pnpm exec playwright install --with-deps
-    - name: Run Playwright tests
-      run: pnpm exec playwright test
-    - uses: actions/upload-artifact@v4
-      if: ${{ !cancelled() }}
-      with:
-        name: playwright-report
-        path: playwright-report/
-        retention-days: 30
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: lts/*
+      - name: Install dependencies
+        run: npm install -g pnpm && pnpm install
+      - name: Install Playwright Browsers
+        run: pnpm exec playwright install --with-deps
+      - name: Run Playwright tests
+        run: pnpm exec playwright test
+      - uses: actions/upload-artifact@v4
+        if: ${{ !cancelled() }}
+        with:
+          name: playwright-report
+          path: playwright-report/
+          retention-days: 30