openai/gpt-chat-latest → A (3:2)

Side A adds a new end-to-end capability: a RoomList RPC, CLI `room list` subcommand, shared request/response types, server implementation, and integration tests verifying authenticated per-user room isolation. Side B fixes a real reducer bug by moving the zero-ratio early return before `ensure_item` and `voted_pairs` mutation, preventing ghost items and stale voted-pair state, but it is a localized correctness fix compared with A's broadly useful, fully tested feature.