~x-ai/grok-latest → B (1:3)

B adds the end-to-end `room create` CLI/RPC path and simplifies the domain (drops `ThreadVisibility`/`RoomState`, rooms become a `HashSet` of private ids) with matching tests and docs—core product surface. A only skips stickied/pinned Reddit children in `parse_children` plus one unit test, a correct but narrow import filter.