List, and unless dry_run delete, one author's demo or unmatched entry rows (operators only)

DESTRUCTIVE: a deleted row cannot be undone and has no backup. demo selects the rows tools/demo-seed minted, its released ones listed under kept and never deleted; unmatched selects engine-written rows charged to no matter; at least one is required, and so is author. The listing and the delete run in ONE transaction in the author's own scope, and the delete removes exactly the listed ids. dry_run answers the list and writes nothing, and is not audited.