a7134bfb80
- Deleting a post / user / term / comment drops its flat row in the adapter delete hook, then WordPress deletes each meta row; sync_from_native upserted NULL for each and brought the row back (512 orphan rows on dev36). With no native value it now only clears the column on an existing row - Verify: tests/live/run.php resync (25/25, entity deletes in dual_write and shadow_read leave no flat row); mut.php T8 flat_row NO-ROW; integration 516 - PR: PR-057b