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/mcp/shared/exceptions.py

@@ -0,0 +1,14 @@
+from mcp.types import ErrorData
+
+
+class McpError(Exception):
+    """
+    Exception type raised when an error arrives over an MCP connection.
+    """
+
+    error: ErrorData
+
+    def __init__(self, error: ErrorData):
+        """Initialize McpError."""
+        super().__init__(error.message)
+        self.error = error