MergeMarkerEntity

A durable record, in the canonical (destination) database, that a given source database has already been folded in by org.meshtastic.core.database.DatabaseMerger. Written inside the same merge transaction as the copied rows, so it commits atomically with them. When org.meshtastic.core.database.DatabaseManager.associateDevice re-runs the merge on the next connection, DatabaseMerger.merge finds the marker at the top of its transaction and skips the whole merge — closing the crash window between the merge commit and the datastore alias write, where a retry would otherwise duplicate the fresh-id packet/discovery rows. Markers share the destination DB's lifecycle: if the canonical DB is LRU-evicted and later recreated empty, its markers vanish with the merged data they describe.