models.json

[Stono]

Hey Hey,
I'm not sure I'm a fan of the way the models.json stuff works.
It feels like a list that's easily out of date in a fast moving space.
For example I recently raised #4837 to add the latest vertex models and then I have #4846 adding support for cloudflare.

Both Cloudflare, and Google, provide endpoints to list their models. So I'm wondering if the providers instead of querying their model.json could query those endpoints instead? They could fail open / have a cache perhaps for safety?