Custom API URls & Langfuse Support

[mrjasonroy]

Many companies (or individuals) use proxies like litellm or kong to proxy llms to control spend, monitor usage and for compliance reasons. These work typically by having a custom base API url and keys.

Proposal:

• Provide environment variables for api urls for each supported provider
• Only show providers with proper keys set up (base url being optional and defaulting to well known)

Companies who don't use a proxy will often use langfuse, which writes to standard opentelemetery endpoints to see how their tools are being used, this is fairly simple to setup using nextjs's observability options.

I am proposing adding both options that are configurable through environment variables to further enhance the platform.

[brrock]

We have openAi like which supports litellm

[brrock]

https://v4.ai-sdk.dev/providers/observability/langfuse#langfuse-observability