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/mdurl/_url.py

@@ -0,0 +1,14 @@
+from __future__ import annotations
+
+from typing import NamedTuple
+
+
+class URL(NamedTuple):
+    protocol: str | None
+    slashes: bool
+    auth: str | None
+    port: str | None
+    hostname: str | None
+    hash: str | None  # noqa: A003
+    search: str | None
+    pathname: str | None