openai/gpt-chat-latest → A (4:1)

Side A adds a complete, focused capability: a new authenticated RoomList RPC, matching CLI subcommand, shared RPC types, and integration tests verifying per-user room visibility and grant isolation. Side B contains a very large UI wiring change, but it also introduces an unrelated planning document (`plan2.md`) and broad routing/auth refactoring without accompanying tests in this patch, making its lasting, verified value less clear than A's precise, well-tested feature.