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/attr/setters.pyi

@@ -0,0 +1,20 @@
+from typing import Any, NewType, NoReturn, TypeVar
+
+from . import Attribute
+from attrs import _OnSetAttrType
+
+_T = TypeVar("_T")
+
+def frozen(
+    instance: Any, attribute: Attribute[Any], new_value: Any
+) -> NoReturn: ...
+def pipe(*setters: _OnSetAttrType) -> _OnSetAttrType: ...
+def validate(instance: Any, attribute: Attribute[_T], new_value: _T) -> _T: ...
+
+# convert is allowed to return Any, because they can be chained using pipe.
+def convert(
+    instance: Any, attribute: Attribute[Any], new_value: Any
+) -> Any: ...
+
+_NoOpType = NewType("_NoOpType", object)
+NO_OP: _NoOpType