~x-ai/grok-latest → A (3:1)

A adds the CLI `room create` path and simplifies the domain model (drop ThreadVisibility/RoomState, rooms as a HashSet, wire/RPC/tests aligned), which is lasting product and design work. B improves one UI surface (chromeless fullscreen compare, edge-history sort/orientation, preview morph, CSS) with real but narrower UX value.