openai/gpt-chat-latest → A (4:3)

Side A introduces a cross-cutting URL routing refactor by centralizing room path encoding/decoding (`room_route_segment`/`room_id_from_route_segment`), updating all server routes and link generation to use a single canonical representation, and adding URL normalization logic (including canonicalization of external URLs such as YouTube links). Although broad, these changes reduce duplicated parsing logic and establish reusable infrastructure, whereas Side B adds a useful but self-contained `RoomList` RPC/CLI feature with good authorization-aware tests but limited architectural impact.