Models and providers move into one registry page

Providers moved out of Settings into Registries → Models, which has three tabs. Models lists every model from every connected provider and flags new ones a sync discovered for review. Providers connects a provider in one sheet: driver, name and key, then the models to enable, with recommended ones ticked. Defaults sets the organization’s default model, decision model and default providers per service.
Provider names are now unique within an organization. Managing providers and
models needs the org:models:manage permission, which replaces the separate
provider permission.