~anthropic/claude-sonnet-latest → B (6:4)

B is a substantial refactor that centralizes duplicated path/URL logic (canonicalize_item, item_path_for_api_in_room, forum_thread_web_url) into a single shared slug-types::paths module with correct-by-construction newtypes (GardenItemUrl, ForumThreadUrl, TildeOntologyPath), reducing duplication between server and types and tightening type safety across many call sites, with tests preserved. A adds a legitimate small feature (RoomList RPC + CLI + integration test) which is useful but narrower in scope and lower architectural impact than B's cross-cutting consolidation.