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/src/test/setup.ts

@@ -8,5 +8,18 @@ const localStorageMock = {
   clear: vi.fn(),
 };
 
+// Ensure localStorage is available on both global and globalThis
 global.localStorage = localStorageMock as any;
+globalThis.localStorage = localStorageMock as any;
+
+// Ensure document is available if jsdom hasn't set it up yet
+if (typeof document === 'undefined') {
+  Object.defineProperty(globalThis, 'document', {
+    value: {
+      body: {},
+    },
+    writable: true,
+  });
+}
+