openai/gpt-chat-latest → B (3:2)

Side B removes hardcoded hostnames by centralizing base URL generation in `app.util/get-base-url`, updates multiple OAuth/callback paths to use it, and makes the frontend derive its base URL from `window.location.origin`, fixing redirects for custom hosts across the application. It also adjusts deployment to run from the staging branch. Side A adds useful UI improvements (vote counts beside compare links, HUD unpin action, tests, and styling), but these are narrower feature enhancements rather than an infrastructure fix that affects many authentication and redirect flows.