List Discoverable Models

List every model the configured provider credentials can reach.

Operator-facing counterpart to GET /v1/models, which serves a curated catalog to API callers. This reports each provider separately and keeps its error, so a provider with a bad key is distinguishable from one with no models. It is master-key gated because a provider error message describes the gateway's own configuration.

Answers from the discovery cache, which a background refresher keeps warm, so the call does not wait on a slow or unreachable provider. Each provider carries the checked_at its result was produced at; a null one has not been dialed yet. Pass refresh=true to force a live re-dial of every provider.