openai/gpt-chat-latest → A (4:1)

Side A delivers substantial architectural improvements: it introduces a background settlement worker that batches vote persistence and ranking recomputation, adds cached ranking reads (`ranked_items_cached`) to avoid recomputing on every HTTP request, and switches ranking rendering from write locks to read locks. It also removes the temporary demo counter and related event/UI code, whereas Side B is primarily a broad type migration from `CanonicalItemUrl` to `ItemId` with widespread mechanical call-site updates and limited new behavior beyond the new identity type.