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/converters.pyi

@@ -0,0 +1,19 @@
+from typing import Callable, Any, overload
+
+from attrs import _ConverterType, _CallableConverterType
+
+@overload
+def pipe(*validators: _CallableConverterType) -> _CallableConverterType: ...
+@overload
+def pipe(*validators: _ConverterType) -> _ConverterType: ...
+@overload
+def optional(converter: _CallableConverterType) -> _CallableConverterType: ...
+@overload
+def optional(converter: _ConverterType) -> _ConverterType: ...
+@overload
+def default_if_none(default: Any) -> _CallableConverterType: ...
+@overload
+def default_if_none(
+    *, factory: Callable[[], Any]
+) -> _CallableConverterType: ...
+def to_bool(val: str | int | bool) -> bool: ...