chore: 添加虚拟环境到仓库

- 添加 backend_service/venv 虚拟环境
- 包含所有Python依赖包
- 注意：虚拟环境约393MB，包含12655个文件

backend_service/venv/lib/python3.13/site-packages/grpc/experimental/gevent.py

@@ -0,0 +1,27 @@
+# Copyright 2018 gRPC authors.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""gRPC's Python gEvent APIs."""
+
+from grpc._cython import cygrpc as _cygrpc
+
+
+def init_gevent():
+    """Patches gRPC's libraries to be compatible with gevent.
+
+    This must be called AFTER the python standard lib has been patched,
+    but BEFORE creating and gRPC objects.
+
+    In order for progress to be made, the application must drive the event loop.
+    """
+    _cygrpc.init_grpc_gevent()