- Remove the super-admin one-time migration from browser local settings into backend AI and speech settings.
- Delete the migration-specific SystemSettings unit test that no longer matches the desired behavior.
- Restore feature, module, testing, and progress docs so settings secrets are documented as backend-managed only.
- Add a super-admin-only settings merge that copies legacy local AI provider keys into an empty backend settings record.
- Add matching migration for legacy Xunfei APPID, APIKey, and APISecret without overwriting existing backend secrets.
- Cover the migration and secret-preservation behavior with SystemSettings unit tests.
- Update feature, module, progress, and testing docs for the settings migration behavior.