Support DashScope OpenAI-compatible API

Hi, thanks for the great project.

I noticed that the current model/API configuration does not seem to support Qwen models through Alibaba Cloud DashScope / Model Studio.

Qwen provides an OpenAI-compatible API endpoint, for example:

OPENAI_API_KEY=<DASHSCOPE_API_KEY>
OPENAI_BASE_URL=https://dashscope.aliyuncs.com/compatible-mode/v1