openai/gpt-chat-latest → B (3:2)

Side B removes scattered hardcoded host/environment logic by introducing a shared `util/get-base-url`, updates multiple OAuth/callback and login redirect paths to use it, uses `window.location.origin` on the frontend, and adjusts deployment to staging, making the application work correctly on custom hosts. Side A fixes vote URL generation to use `display_path` instead of storage URLs and substantially strengthens the browser test by exercising all 45 pairwise votes and verifying the final ranking, but its functional impact is narrower than the cross-cutting redirect/configuration fix in Side B.