After this migration, all writes must go through the new schema; the old column is dropped Monday.
From v2 onward, every endpoint requires an auth token and unauthenticated calls will 401.
Once we merge this, the config format is frozen and older config files stop loading.
Starting next sprint, no PR merges without a passing coverage gate.
After the cutover, the legacy API is read-only and shuts down in 30 days.
