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/cachetools/keys.py

@@ -0,0 +1,62 @@
+"""Key functions for memoizing decorators."""
+
+__all__ = ("hashkey", "methodkey", "typedkey", "typedmethodkey")
+
+
+class _HashedTuple(tuple):
+    """A tuple that ensures that hash() will be called no more than once
+    per element, since cache decorators will hash the key multiple
+    times on a cache miss.  See also _HashedSeq in the standard
+    library functools implementation.
+
+    """
+
+    __hashvalue = None
+
+    def __hash__(self, hash=tuple.__hash__):
+        hashvalue = self.__hashvalue
+        if hashvalue is None:
+            self.__hashvalue = hashvalue = hash(self)
+        return hashvalue
+
+    def __add__(self, other, add=tuple.__add__):
+        return _HashedTuple(add(self, other))
+
+    def __radd__(self, other, add=tuple.__add__):
+        return _HashedTuple(add(other, self))
+
+    def __getstate__(self):
+        return {}
+
+
+# A sentinel for separating args from kwargs.  Using the class itself
+# ensures uniqueness and preserves identity when pickling/unpickling.
+_kwmark = (_HashedTuple,)
+
+
+def hashkey(*args, **kwargs):
+    """Return a cache key for the specified hashable arguments."""
+
+    if kwargs:
+        return _HashedTuple(args + sum(sorted(kwargs.items()), _kwmark))
+    else:
+        return _HashedTuple(args)
+
+
+def methodkey(self, *args, **kwargs):
+    """Return a cache key for use with cached methods."""
+    return hashkey(*args, **kwargs)
+
+
+def typedkey(*args, **kwargs):
+    """Return a typed cache key for the specified hashable arguments."""
+
+    key = hashkey(*args, **kwargs)
+    key += tuple(type(v) for v in args)
+    key += tuple(type(v) for _, v in sorted(kwargs.items()))
+    return key
+
+
+def typedmethodkey(self, *args, **kwargs):
+    """Return a typed cache key for use with cached methods."""
+    return typedkey(*args, **kwargs)