feat: support Cortecs

[harmw]

• I have read CONTRIBUTING.md.
• I have created a discussion that was approved by a maintainer (for new features).

This implements Cortecs, the European LLM router.

[andreynering]

Thank you @harmw!

I looks good overall. I added a few suggestions below.

I'd also like to ask you to properly test it, since you have a key. To do that, just run this server with go run . and run Crush with env CATWALK_URL=http://localhost:8080 crush.

[harmw]

✅ tested it (using kimi-k2.5)

Found a bug as well 🤔 looks like the last used model is not refreshed (which makes sense, b/c how would crush know it needs to refresh), as I had changed the MaxTokens value.

Is this a familiar observation? Should there maybe be some sort of refresh providers option?

nvm: crush update-providers

I should maybe consider writing some dev docs on how to manage/test providers here 😛

[andreynering]

Thank you @harmw!

I just pushed two commits with cosmetic changes.