openai/gpt-chat-latest → A (4:1)

Side A removes the legacy GitDiscovery projection path and makes the application consistently evidence-driven: it deletes fallback lookup code, simplifies epoch/commit pages to require Evidence envelopes, makes Emission evidence metadata required, and updates tests to enforce the new behavior. Side B is a useful infrastructure/configuration cleanup that centralizes base URL generation via a shared utility, uses the current browser origin for frontend redirects, and adjusts deployment to the staging branch, but its impact is narrower and primarily configuration-oriented.