fix: 补充测试桩缺失的接口方法

backend/internal/server/api_contract_test.go

@@ -618,6 +618,14 @@ func (stubApiKeyCache) DeleteAuthCache(ctx context.Context, key string) error {
 	return nil
 }
 
+func (stubApiKeyCache) PublishAuthCacheInvalidation(ctx context.Context, cacheKey string) error {
+	return nil
+}
+
+func (stubApiKeyCache) SubscribeAuthCacheInvalidation(ctx context.Context, handler func(cacheKey string)) error {
+	return nil
+}
+
 type stubGroupRepo struct{}
 
 func (stubGroupRepo) Create(ctx context.Context, group *service.Group) error {

backend/internal/service/api_key_service_cache_test.go

@@ -142,6 +142,14 @@ func (s *authCacheStub) DeleteAuthCache(ctx context.Context, key string) error {
 	return nil
 }
 
+func (s *authCacheStub) PublishAuthCacheInvalidation(ctx context.Context, cacheKey string) error {
+	return nil
+}
+
+func (s *authCacheStub) SubscribeAuthCacheInvalidation(ctx context.Context, handler func(cacheKey string)) error {
+	return nil
+}
+
 func TestAPIKeyService_GetByKey_UsesL2Cache(t *testing.T) {
 	cache := &authCacheStub{}
 	repo := &authRepoStub{

backend/internal/service/api_key_service_delete_test.go

@@ -168,6 +168,14 @@ func (s *apiKeyCacheStub) DeleteAuthCache(ctx context.Context, key string) error
 	return nil
 }
 
+func (s *apiKeyCacheStub) PublishAuthCacheInvalidation(ctx context.Context, cacheKey string) error {
+	return nil
+}
+
+func (s *apiKeyCacheStub) SubscribeAuthCacheInvalidation(ctx context.Context, handler func(cacheKey string)) error {
+	return nil
+}
+
 // TestApiKeyService_Delete_OwnerMismatch 测试非所有者尝试删除时返回权限错误。
 // 预期行为：
 //   - GetKeyAndOwnerID 返回所有者 ID 为 1