_anthropic_catalog() returned the curated list as a plain list when the live
/v1/models fetch failed, so a transient outage on a proxy base_url was cached
with the full 1h TTL as if it were the account's/proxy's real catalog, and
neither a same-credentials restart nor Refresh Models could shake it before the
TTL lapsed. Wrap the fallback return in CuratedFallbackModels, the placeholder
type #107391 introduced for the same class of bug.
Salvaged from #121248 (the Anthropic half; the Codex half lands via the
typed-fallback commit before this one).
ba2a38e771