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/aiosignal/__init__.py

@@ -0,0 +1,59 @@
+import sys
+from typing import Any, Awaitable, Callable, TypeVar
+
+from frozenlist import FrozenList
+
+if sys.version_info >= (3, 11):
+    from typing import Unpack
+else:
+    from typing_extensions import Unpack
+
+if sys.version_info >= (3, 13):
+    from typing import TypeVarTuple
+else:
+    from typing_extensions import TypeVarTuple
+
+_T = TypeVar("_T")
+_Ts = TypeVarTuple("_Ts", default=Unpack[tuple[()]])
+
+__version__ = "1.4.0"
+
+__all__ = ("Signal",)
+
+
+class Signal(FrozenList[Callable[[Unpack[_Ts]], Awaitable[object]]]):
+    """Coroutine-based signal implementation.
+
+    To connect a callback to a signal, use any list method.
+
+    Signals are fired using the send() coroutine, which takes named
+    arguments.
+    """
+
+    __slots__ = ("_owner",)
+
+    def __init__(self, owner: object):
+        super().__init__()
+        self._owner = owner
+
+    def __repr__(self) -> str:
+        return "<Signal owner={}, frozen={}, {!r}>".format(
+            self._owner, self.frozen, list(self)
+        )
+
+    async def send(self, *args: Unpack[_Ts], **kwargs: Any) -> None:
+        """
+        Sends data to all registered receivers.
+        """
+        if not self.frozen:
+            raise RuntimeError("Cannot send non-frozen signal.")
+
+        for receiver in self:
+            await receiver(*args, **kwargs)
+
+    def __call__(
+        self, func: Callable[[Unpack[_Ts]], Awaitable[_T]]
+    ) -> Callable[[Unpack[_Ts]], Awaitable[_T]]:
+        """Decorator to add a function to this Signal."""
+        self.append(func)
+        return func