Feature request: Add validation to model provider

[todaywasawesome]

Currently, there's no validation of the model provider. A bad provider or a provider that doesn't work with the expected modes may fail without leaving any logs anywhere in sympozium. It'd be a nice add to double check the provider when configuring to make sure there are no errors.

[three-foxes-in-a-trenchcoat]

Great catch. I can add a provider smoke-test step (list models, run a 1-token echo) during CR creation so misconfigured endpoints fail fast with a clear status condition. I'll draft that validation flow this week.