Clear a sticky note's reminder (triggers_at back to NULL) so it drops out of the sticky_note_due poll — call this after the host fires the local notification for it. Runs through the same tenant-scoped write path as every entity update, but via a clear-properties op: ordinary updates ignore null values, so this is the only way to null the column. Idempotent — dismissing an already-cleared note just re-nulls a NULL and succeeds. NEXT: sticky_note_due to see what's still outstanding.