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/tokenizers/tokenizer.py

@@ -0,0 +1,45 @@
+# Copyright (c) Alibaba, Inc. and its affiliates.
+
+import os
+from typing import List
+
+from dashscope.common.error import UnsupportedModel
+from dashscope.tokenizers.qwen_tokenizer import QwenTokenizer
+
+from .tokenizer_base import Tokenizer
+
+QWEN_SERIALS = ['qwen-7b-chat', 'qwen-turbo', 'qwen-plus', 'qwen-max']
+current_path = os.path.dirname(os.path.abspath(__file__))
+root_path = os.path.dirname(current_path)
+
+
+def get_tokenizer(model: str) -> Tokenizer:
+    """Get a tokenizer based on model name.
+
+    Args:
+        model (str): The model name.
+
+    Raises:
+        UnsupportedModel: Not support model
+
+    Returns:
+        Tokenizer: The  `Tokenizer` of the model.
+    """
+    if model in QWEN_SERIALS:
+        return QwenTokenizer(
+            os.path.join(root_path, 'resources', 'qwen.tiktoken'))
+    elif model.startswith('qwen'):
+        return QwenTokenizer(
+            os.path.join(root_path, 'resources', 'qwen.tiktoken'))
+    else:
+        raise UnsupportedModel(
+            f'Not support model: {model}, currently only support qwen models.')
+
+
+def list_tokenizers() -> List[str]:
+    """List support models
+
+    Returns:
+        List[str]: The model list.
+    """
+    return QWEN_SERIALS