9410d6daaa
Internal rename: DELETE_MARKER -> CLOSE_MARKER, DeleteMarker -> CloseMarker, is_deleted -> is_closed. The batch UUID is dropped; undo now groups cases by their exact closed_at timestamp, which bulk-close writes identically across its selection while per-case close writes a unique stamp. Behavior unchanged. No migration (project is pre-production); legacy .deleted files in tmpdata were removed manually.