test: add comprehensive test coverage and improve code quality

- Add new test files for auth, service, and handler modules
- Improve test organization and coverage
- Refactor code for better maintainability
- Add captcha, settings, stats, and theme handler tests
- Add auth module tests (CAS, OAuth, password, SSO, state)
- Add service layer tests for auth, export, permissions, roles
- All Go tests pass (exit code 0)
- All frontend tests pass (325 tests in 59 files)

internal/api/handler/webhook_handler_test.go

@@ -101,9 +101,12 @@ func setupWebhookTestServer(t *testing.T) (*httptest.Server, *gorm.DB, string, f
 
 	userRepo := repository.NewUserRepository(db)
 	roleRepo := repository.NewRoleRepository(db)
+	_ = roleRepo // kept for future use
 	permissionRepo := repository.NewPermissionRepository(db)
+	_ = permissionRepo
 	userRoleRepo := repository.NewUserRoleRepository(db)
 	rolePermissionRepo := repository.NewRolePermissionRepository(db)
+	_ = rolePermissionRepo
 
 	authSvc := service.NewAuthService(userRepo, nil, jwtManager, cacheManager, 8, 5, 15*time.Minute)
 	authSvc.SetRoleRepositories(userRoleRepo, roleRepo)
@@ -113,7 +116,7 @@ func setupWebhookTestServer(t *testing.T) (*httptest.Server, *gorm.DB, string, f
 	rateLimitCfg := config.RateLimitConfig{}
 	rateLimitMiddleware := middleware.NewRateLimitMiddleware(rateLimitCfg)
 	authMiddleware := middleware.NewAuthMiddleware(
-		jwtManager, userRepo, userRoleRepo, roleRepo, rolePermissionRepo, permissionRepo, l1Cache,
+		jwtManager, userRepo, userRoleRepo, l1Cache,
 	)
 	authMiddleware.SetCacheManager(cacheManager)