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/lib/__tests__/api.test.ts

@@ -24,7 +24,13 @@ describe('apiClient', () => {
       expires: '2099-01-01',
     });
     
-    (global.localStorage.getItem as any).mockReturnValue('club-1');
+    // Mock document.cookie with X-Tenant-Id
+    Object.defineProperty(document, 'cookie', {
+      value: 'X-Tenant-Id=club-1',
+      writable: true,
+      configurable: true,
+    });
+    
     (global.fetch as any).mockResolvedValue({
       ok: true,
       status: 200,
@@ -143,8 +149,12 @@ describe('apiClient', () => {
     expect(callHeaders.Authorization).toBeUndefined();
   });
 
-  it('should not add X-Tenant-Id header when no active club', async () => {
-    (global.localStorage.getItem as any).mockReturnValueOnce(null);
+  it('should not add X-Tenant-Id header when no cookie present', async () => {
+    Object.defineProperty(document, 'cookie', {
+      value: '',
+      writable: true,
+      configurable: true,
+    });
 
     await apiClient('/api/test');
 

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,
+  });
+}
+