[FEATURE]: Help user discover their provider/model pair availability

Feature hasn't been suggested before.

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Describe the enhancement you want to request

I am missing an easy way to check in with each of the models listed by opencode models to see which ones are actually available via API for me to use, today, now.

I think of this action as a "roll call", like the one you do at the morning in school (or in prison, eheh) to check for any absence.

I have actually been doing this already, with a bash for-loop and a lot of opencode run, but that way is _painfully slow for obvious reasons - launching opencode from scratch a hundred times, new sessions, managing timeouts ... and then on top of that, I have to parse the somewhat unstructured output of my survey. I don't want to invest more time in a custom script for this - opencode already knows how to switch between its provider-model pairs - there should be a built-in way to perform this type of survey/diagnostic on behalf of the user.