When --provider <name> is passed and no provider with that name exists on
the server, the CLI now checks if the name is a recognized provider type
(e.g. claude, nvidia, github). If it is, the provider is auto-created
from local credentials using the same discovery flow as inferred providers.
If the name is not a recognized type, the CLI returns a clear error
instead of deferring validation to the server.
This eliminates the FailedPrecondition error that occurred when passing
--provider nvidia on a fresh cluster where no providers had been created
yet.
Drew Newberry