Both stale-pin detections exempt only '' and 'auto':
- desktop persistentStaleAux banner (model-settings.tsx)
- switch-time stale_aux response (hermes_cli/web_server.py)
'main' is a backend-supported alias (auxiliary_client._normalize_aux_provider)
meaning "follow the active main provider", so aux slots pinned to it can
never be stale. The false positive fires for users following Moonshot's
official Hermes integration guide, which prescribes
auxiliary.vision.provider: main.
Exempt the alias in both places and add a regression test.