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/uvloop/handles/pipe.pxd

@@ -0,0 +1,33 @@
+cdef class UnixServer(UVStreamServer):
+
+    cdef bind(self, str path)
+
+    @staticmethod
+    cdef UnixServer new(Loop loop, object protocol_factory, Server server,
+                        object backlog,
+                        object ssl,
+                        object ssl_handshake_timeout,
+                        object ssl_shutdown_timeout)
+
+
+cdef class UnixTransport(UVStream):
+
+    @staticmethod
+    cdef UnixTransport new(Loop loop, object protocol, Server server,
+                           object waiter, object context)
+
+    cdef connect(self, char* addr)
+
+
+cdef class ReadUnixTransport(UVStream):
+
+    @staticmethod
+    cdef ReadUnixTransport new(Loop loop, object protocol, Server server,
+                               object waiter)
+
+
+cdef class WriteUnixTransport(UVStream):
+
+    @staticmethod
+    cdef WriteUnixTransport new(Loop loop, object protocol, Server server,
+                                object waiter)