openai/gpt-chat-latest → A (4:1)

Side A delivers a substantive feature by adding a `room create` CLI command end-to-end, wiring it through RPC, documenting its use, and simplifying the server model by removing the unused room visibility concept and replacing the room registry with a `HashSet` of room IDs. Side B mainly fixes lock-scoping around `RwLock` reads to avoid potential deadlocks, adds one integration test, and improves test harness timeouts/logging, which are valuable but narrower in long-term impact than the new user-facing capability and associated design cleanup in Side A.