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

backend/WorkClub.Tests.Integration/Infrastructure/CustomWebApplicationFactory.cs

@@ -51,11 +51,26 @@ public class CustomWebApplicationFactory<TProgram> : WebApplicationFactory<TProg
             services.AddAuthentication(defaultScheme: "Test")
                 .AddScheme<AuthenticationSchemeOptions, TestAuthHandler>("Test", options => { });
 
-            // Build service provider and ensure database created
+            // Build service provider and run migrations
             var sp = services.BuildServiceProvider();
             using var scope = sp.CreateScope();
             var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
-            db.Database.EnsureCreated();
+            db.Database.Migrate();
+            
+            using var conn = new Npgsql.NpgsqlConnection(_postgresContainer.GetConnectionString());
+            conn.Open();
+            using var cmd = conn.CreateCommand();
+            cmd.CommandText = @"
+                DO $$ BEGIN
+                IF NOT EXISTS (SELECT 1 FROM pg_roles WHERE rolname = 'rls_test_user') THEN
+                    CREATE USER rls_test_user WITH PASSWORD 'rlspass';
+                    GRANT CONNECT ON DATABASE workclub_test TO rls_test_user;
+                    GRANT SELECT, INSERT, UPDATE, DELETE ON ALL TABLES IN SCHEMA public TO rls_test_user;
+                    GRANT USAGE, SELECT ON ALL SEQUENCES IN SCHEMA public TO rls_test_user;
+                END IF;
+                END $$;
+            ";
+            cmd.ExecuteNonQuery();
         });
 
         builder.UseEnvironment("Test");