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/pydantic_settings/utils.py

@@ -0,0 +1,42 @@
+import types
+from pathlib import Path
+from typing import Any, _GenericAlias, get_origin  # type: ignore [attr-defined]
+
+_PATH_TYPE_LABELS = {
+    Path.is_dir: 'directory',
+    Path.is_file: 'file',
+    Path.is_mount: 'mount point',
+    Path.is_symlink: 'symlink',
+    Path.is_block_device: 'block device',
+    Path.is_char_device: 'char device',
+    Path.is_fifo: 'FIFO',
+    Path.is_socket: 'socket',
+}
+
+
+def path_type_label(p: Path) -> str:
+    """
+    Find out what sort of thing a path is.
+    """
+    assert p.exists(), 'path does not exist'
+    for method, name in _PATH_TYPE_LABELS.items():
+        if method(p):
+            return name
+
+    return 'unknown'  # pragma: no cover
+
+
+# TODO remove and replace usage by `isinstance(cls, type) and issubclass(cls, class_or_tuple)`
+# once we drop support for Python 3.10.
+def _lenient_issubclass(cls: Any, class_or_tuple: Any) -> bool:  # pragma: no cover
+    try:
+        return isinstance(cls, type) and issubclass(cls, class_or_tuple)
+    except TypeError:
+        if get_origin(cls) is not None:
+            # Up until Python 3.10, isinstance(<generic_alias>, type) is True
+            # (e.g. list[int])
+            return False
+        raise
+
+
+_WithArgsTypes = (_GenericAlias, types.GenericAlias, types.UnionType)