- Migrate iterates migrationSets, so the startup summary, --pretend, the
production question, the applied lines and migrate:status --json read
the same list; each set keeps its error wording through a label
- migrate reports pending-before minus pending-after as its applied
lines and result line, also when Migrate fails partway (then it prints
what was applied and returns the error)
- TestMigrateAppliedLines (Docker) pins both (WR-07)