Model catalog fetch now reports a distinct 'credential cannot read served list' refusal

When Claude Code tries to fetch the current list of available models from the server and is refused specifically because the credential in use doesn't have permission to see it, a new handler now fires a model_catalog_primary telemetry event recording the decision as 'off' with the reason credential_scope, and prints a console note explaining that the built-in, compiled-in model list is being used instead.