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/google/api/label.proto

@@ -0,0 +1,47 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.api;
+
+option go_package = "google.golang.org/genproto/googleapis/api/label;label";
+option java_multiple_files = true;
+option java_outer_classname = "LabelProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+// A description of a label.
+message LabelDescriptor {
+  // Value types that can be used as label values.
+  enum ValueType {
+    // A variable-length string. This is the default.
+    STRING = 0;
+
+    // Boolean; true or false.
+    BOOL = 1;
+
+    // A 64-bit signed integer.
+    INT64 = 2;
+  }
+
+  // The label key.
+  string key = 1;
+
+  // The type of data that can be assigned to the label.
+  ValueType value_type = 2;
+
+  // A human-readable description for the label.
+  string description = 3;
+}