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/dashscope/common/env.py

@@ -0,0 +1,22 @@
+# Copyright (c) Alibaba, Inc. and its affiliates.
+
+import os
+
+from dashscope.common.constants import (DASHSCOPE_API_KEY_ENV,
+                                        DASHSCOPE_API_KEY_FILE_PATH_ENV,
+                                        DASHSCOPE_API_REGION_ENV,
+                                        DASHSCOPE_API_VERSION_ENV)
+
+api_region = os.environ.get(DASHSCOPE_API_REGION_ENV, 'cn-beijing')
+api_version = os.environ.get(DASHSCOPE_API_VERSION_ENV, 'v1')
+# read the api key from env
+api_key = os.environ.get(DASHSCOPE_API_KEY_ENV)
+api_key_file_path = os.environ.get(DASHSCOPE_API_KEY_FILE_PATH_ENV)
+
+# define api base url, ensure end /
+base_http_api_url = os.environ.get(
+    'DASHSCOPE_HTTP_BASE_URL',
+    'https://dashscope.aliyuncs.com/api/%s' % (api_version))
+base_websocket_api_url = os.environ.get(
+    'DASHSCOPE_WEBSOCKET_BASE_URL',
+    'wss://dashscope.aliyuncs.com/api-ws/%s/inference' % (api_version))