openai/gpt-chat-latest → B (5:1)

Side B performs a broad but coherent type-safety refactor by changing `resolve_item` to return `CanonicalItemUrl`, propagating canonical URL types through validation, ranking, RPCs, and connectivity logic, and adding `Deref<str>` support to URL newtypes to reduce string conversions. Side A removes a redundant zero-ratio guard and updates the corresponding test to reflect that zero-weight edges are skipped later while items are still registered, which is a comparatively small cleanup with limited architectural impact.