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/overrides/enforce.py

@@ -0,0 +1,58 @@
+from abc import ABCMeta
+
+
+class EnforceOverridesMeta(ABCMeta):
+    def __new__(mcls, name, bases, namespace, **kwargs):
+        # Ignore any methods defined on the metaclass when enforcing overrides.
+        for method in dir(mcls):
+            if not method.startswith("__") and method != "mro":
+                value = getattr(mcls, method)
+                if not isinstance(value, (bool, str, int, float, tuple, list, dict)):
+                    setattr(getattr(mcls, method), "__ignored__", True)
+
+        cls = super().__new__(mcls, name, bases, namespace, **kwargs)
+        for name, value in namespace.items():
+            mcls._check_if_overrides_final_method(name, bases)
+            if not name.startswith("__"):
+                value = mcls._handle_special_value(value)
+                mcls._check_if_overrides_without_overrides_decorator(name, value, bases)
+        return cls
+
+    @staticmethod
+    def _check_if_overrides_without_overrides_decorator(name, value, bases):
+        is_override = getattr(value, "__override__", False)
+        for base in bases:
+            base_class_method = getattr(base, name, False)
+            if (
+                not base_class_method
+                or not callable(base_class_method)
+                or getattr(base_class_method, "__ignored__", False)
+            ):
+                continue
+            if not is_override:
+                raise TypeError(
+                    f"Method {name} overrides method from {base} but does not have @override decorator"
+                )
+
+    @staticmethod
+    def _check_if_overrides_final_method(name, bases):
+        for base in bases:
+            base_class_method = getattr(base, name, False)
+            # `__final__` is added by `@final` decorator
+            if getattr(base_class_method, "__final__", False):
+                raise TypeError(
+                    f"Method {name} is finalized in {base}, it cannot be overridden"
+                )
+
+    @staticmethod
+    def _handle_special_value(value):
+        if isinstance(value, classmethod) or isinstance(value, staticmethod):
+            value = value.__get__(None, dict)
+        elif isinstance(value, property):
+            value = value.fget
+        return value
+
+
+class EnforceOverrides(metaclass=EnforceOverridesMeta):
+    "Use this as the parent class for your custom classes"
+    pass