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/numpy/f2py/func2subr.pyi

@@ -0,0 +1,7 @@
+from .auxfuncs import _Bool, _ROut, _Var
+
+def var2fixfortran(vars: _Var, a: str, fa: str | None = None, f90mode: _Bool | None = None) -> str: ...
+def useiso_c_binding(rout: _ROut) -> bool: ...
+def createfuncwrapper(rout: _ROut, signature: int = 0) -> str: ...
+def createsubrwrapper(rout: _ROut, signature: int = 0) -> str: ...
+def assubr(rout: _ROut) -> tuple[dict[str, str], str]: ...