No-auth providers (OpenCode Free) have no connection row, so handleImportModels returned early and /api/providers/[id]/models 404'd — the import button silently no-op'd. The route now serves the provider's registry/static model catalog when called with a no-auth provider id, and handleImportModels falls back to the provider id when there is no connection. Test: route returns the opencode catalog (source local_catalog) and still 404s for unknown ids.
