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

Side B fixes a real, systemic bug (hardcoded staging hostnames breaking OAuth callbacks and redirects across multiple services) by consolidating logic into a single util.get-base-url helper, reducing duplication and future maintenance burden across 6+ files. Side A is a legitimate but narrow UI feature (clickable unpin icon) with reasonable test coverage, but it's more localized and lower-impact than fixing broken cross-service redirect infrastructure.