With sqlx 0.9 honouring `-- no-transaction`, 0007 loses its
movie_releases_backup stash like 0014 did, and 0021 gains
the CHECK (title <> '') that #153 abandoned because the 0.8
migrator could not run a rebuild with foreign keys off. The
rebuild test now enters at migration 6 so the child links
ride through all three rebuilds, and a new test proves the
'' -> 'TBA' backfill and the rejection of new empty titles.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>