~x-ai/grok-latest → B (2:3)

B introduces lasting core routing design (ItemId browse_href/from_browse_uri, /~/ paths, shared helpers, and tests) and simplifies the HTML stack, whereas much of its diff is theme/CSS deletion. A is a solid but narrower fix: centralizing get-base-url/HOSTNAME and window.location.origin for OAuth redirects plus pointing Fly deploys at staging.