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/cbhandles.pxd

@@ -0,0 +1,39 @@
+cdef class Handle:
+    cdef:
+        Loop loop
+        object context
+        bint _cancelled
+
+        str meth_name
+        int cb_type
+        void *callback
+        object arg1, arg2, arg3, arg4
+
+        object __weakref__
+
+        readonly _source_traceback
+
+    cdef inline _set_loop(self, Loop loop)
+    cdef inline _set_context(self, object context)
+
+    cdef inline _run(self)
+    cdef _cancel(self)
+
+    cdef _format_handle(self)
+
+
+cdef class TimerHandle:
+    cdef:
+        object callback
+        tuple args
+        bint _cancelled
+        UVTimer timer
+        Loop loop
+        object context
+        tuple _debug_info
+        object __weakref__
+        object _when
+
+    cdef _run(self)
+    cdef _cancel(self)
+    cdef inline _clear(self)