openai/gpt-chat-latest → A (4:1)

Side A performs a broad architectural migration from `CanonicalItemUrl` strings to a first-class `ItemId` type, adds the new `types/src/item_id.rs` and `item_wire.rs` modules, and propagates the stronger identity model through reducers, ranking, routing, APIs, and tests. Side B is an important targeted security fix—introducing `ammonia` to sanitize untrusted Reddit HTML before `PreEscaped` rendering with tests—but its scope is limited to one rendering path, while Side A changes a core project abstraction with lasting impact across the codebase.