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/rich/_stack.py

@@ -0,0 +1,16 @@
+from typing import List, TypeVar
+
+T = TypeVar("T")
+
+
+class Stack(List[T]):
+    """A small shim over builtin list."""
+
+    @property
+    def top(self) -> T:
+        """Get top of stack."""
+        return self[-1]
+
+    def push(self, item: T) -> None:
+        """Push an item on to the stack (append in stack nomenclature)."""
+        self.append(item)