The room card's Join (deep links, permalinks, history) and /join joined
through mx.joinRoom and never filed the DM. They now go through
activateEstateRoom. A gateway 5xx, or a status with no errcode, has an unknown
outcome like a dropped connection: the entry stays and the tap is retryable.
The harness gains Soul's s6 deeplink and gw504 drives.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>