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/overrides/final.py

@@ -0,0 +1,45 @@
+#
+#  Copyright 2016 Keunhong Lee
+#
+#  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.
+#
+from types import FunctionType
+from typing import Callable, TypeVar, Union
+
+_WrappedMethod = TypeVar("_WrappedMethod", bound=Union[FunctionType, Callable])
+
+
+def final(method: _WrappedMethod) -> _WrappedMethod:
+    """Decorator to indicate that the decorated method is finalized and cannot be overridden.
+    The decorator code is executed while loading class. Using this method
+    should have minimal runtime performance implications.
+    Currently, only methods with @override are checked.
+
+    How to use:
+    from overrides import final
+
+    class SuperClass(object):
+        @final
+        def method(self):
+          return 2
+
+    class SubClass(SuperClass):
+        @override
+        def method(self): #causes an error
+            return 1
+
+    :raises AssertionError: if there exists a match in sub classes for the method name
+    :return: method
+    """
+    setattr(method, "__final__", True)
+    return method