Request: Add openrouter.ai endpoint support

Hi,

I have tried adding the openrouter.ai into ChainForge as the custom provider, but it always responsed"Error encountered while calling custom provider function: 400 Client Error: Bad Request for url: https://openrouter.ai/api/v1/chat/completions".

I'm not a developer, I have tried my best to debug this issue with GPT 4 turbo for multiple hours, and it was still not working:(

Could you please consider adding this endpoint like toghether.ai as the native endpoint when you are free?
https://openrouter.ai/docs#quick-start

This endpoint is really popular in the market.

Really appreciate if you can consider this request!