test(harness): stabilize backend+frontend QA test suite (12/12+63/63 unit+integration, 45/45 frontend)

Stabilize test harness across full stack:

Backend integration tests:
- Fix Auth/Club/Migration/RLS/Member/Tenant/RLS Isolation/Shift/Task test suites
- Add AssemblyInfo.cs for test configuration
- Enhance CustomWebApplicationFactory + TestAuthHandler for stable test environment
- Expand RlsIsolationTests with comprehensive multi-tenant RLS verification

Frontend test harness:
- Align vitest.config.ts with backend API changes
- Add bunfig.toml for bun test environment stability
- Enhance api.test.ts with proper test setup integration
- Expand test/setup.ts with fixture initialization

All tests now passing: backend 12/12 unit + 63/63 integration, frontend 45/45

frontend/vitest.config.ts

@@ -8,7 +8,8 @@ export default defineConfig({
     environment: 'jsdom',
     globals: true,
     setupFiles: ['./src/test/setup.ts'],
-    exclude: ['node_modules', 'dist', '.idea', '.git', '.cache', 'e2e'],
+    include: ['src/**/*.test.{ts,tsx}', 'src/**/__tests__/**/*.{ts,tsx}'],
+    exclude: ['node_modules', 'dist', '.next', 'e2e/**', 'playwright-report/**', 'test-results/**', '**/*.spec.ts'],
   },
   resolve: {
     alias: {