openai/gpt-chat-latest → A (4:1)

Side A performs a broad, type-safe refactor by changing `resolve_item` to return `CanonicalItemUrl`, propagating canonical URL types through validation, ranking, pair selection, and connectivity logic, and adding `Deref<Target=str>` for URL newtypes to reduce conversions. This removes repeated parsing/wrapping (`CanonicalItemUrl(it.clone())`, `parse(...)`) and makes canonical IDs first-class across the API, whereas Side B is a localized UI enhancement that makes pinned child-group icons clickable to unpin and adds corresponding browser tests and CSS.