#1004 mg verify fails on highway_db_v2: jumper_initial row has NULL checksum, parallel_join_counter applied with a pre-commit checksum

EARS: When mg verify runs on the merged migration set against highway_db_v2, it shall report no mismatch. Found during #971 (forensic read-only data dump of public._migrations, verify run on a scratch copy only): 1. 01KGX7TA6RZGZFE4RYVNGBMP78 jumper_initial: row inserted by the entrypoint (never executed, by design) with checksum NULL; its file is excluded from the merged set because executing it fails and its down drops schema jumper cascade. 2. 01KGW00000000000000000001 parallel_join_counter: applied 2026-06-22 23:06 with checksum d467c1cd...; the only commit of the file (engine 9c9ec17, 2026-06-23 01:04) has checksum 6424bb98.... A catalog comparison of a fresh build against the live schema shows no resulting difference. 3. Live jumper.complete_run differs from the migration-built body in whitespace only (hand-applied SQL). Fixing 1 and 2 means changing _migrations rows on the live DB, which is an owner decision (no API; mg fix only repairs failed rows).