test: fix celery mock path for generation retry tests

tests/integration/test_task_center_api.py

@@ -428,7 +428,7 @@ class TestRetryProjectTask:
         assert resp.status_code == 400
         assert "Unsupported" in resp.json()["detail"]
 
-    @patch("app.api.routes.task_center.celery_app")
+    @patch("app.core.task_enqueue.celery_app")
     def test_retry_failed_generation_task(self, mock_celery, client):
         """重试失败的 generation 任务成功。"""
         mock_celery.send_task = MagicMock()
@@ -581,7 +581,7 @@ class TestRetryProjectTask:
 class TestTaskCenterCrossEndpoint:
     """任务中心跨端点集成测试。"""
 
-    @patch("app.api.routes.task_center.celery_app")
+    @patch("app.core.task_enqueue.celery_app")
     def test_list_then_retry_then_list(self, mock_celery, client):
         """列出任务 → 重试失败任务 → 再列出验证新任务。"""
         mock_celery.send_task = MagicMock()