~x-ai/grok-latest → B (2:5)

B adds lasting core product logic: bridge-first pair selection in pair.rs (with unit tests), a full /vote compare UI with post-vote edge-history morphing, and ItemId::from_storage normalization plus integration coverage. A mostly plumbs cookie-based theme through layout/handlers and secondary private-room wire URL helpers in RPC—useful polish and API consistency, but less foundational than the ranking/vote path work.