Feature Request: Support Custom Third-Party API Endpoint (User-Defined URL)

[qzchen2022]

Hi,

First, thank you for this excellent project — it has been incredibly useful.

I would like to propose a feature request that could improve flexibility:

Would it be possible to add support for a custom third-party API endpoint, where users can manually provide their own API URL?

[qzchen2022]

Hi, by replacing the openai sdk with the google sdk and canceling the gemini method for the /openai/ completion of the url, third-party implementation can be achieved.

[lartpang]

@qzchen2022 Myabe you can try this PR #20