Add Mistral, use "ai" lib

[keturiosakys]

This PR consolidates interfaces with AI providers using the ai library from Vercel and adds support for Mistral.

[pkg-pr-new]

Open in Stackblitz

pnpm add https://pkg.pr.new/fiberplane/fpx/@fiberplane/studio@321

pnpm add https://pkg.pr.new/fiberplane/fpx/@fiberplane/hono-otel@321

commit: 9ed7d96

[brettimus]

i'd say either remove this chunk or uncomment

part of the logic behind this was to allow the end user to delete api keys... but i don't think that worked anyhow

[brettimus]

approved just needs to fix the things i identified when testing

we will probably wanna check out ade's pr after this too, to look for possible regressions ¯_(ツ)_/¯

[brettimus]

two things:

1. Don't forget to cut a new release of the types package
2. Changelog!