~anthropic/claude-sonnet-latest → B (3:2)

Side B fixes a real, broad bug: hardcoded hostnames/URLs (oauth callbacks, redirects, deploy branch) across multiple modules were centralized into a single util function that respects HOSTNAME/window.location, which is a genuine correctness/maintainability improvement affecting deploy and auth flows. Side A is a UI polish commit (vote counts, HUD unpin button, CSS tweaks, tests) that's fine but more localized cosmetic/UX churn with less structural impact than fixing broken environment-dependent redirect logic.