POST /v1/runs/{run}/purge: the trash was emptied, and this run is gone.
Everything this device holds about it: the ledger's rows, its authority record, and its working folder when Koru made that folder. A run scoped to a project ran inside the person's own repository, and that directory was theirs before the run and is theirs after - folder says which of those happened, because a trash that quietly did less than it offered teaches somebody that it did more.
The Run document is not purged here: it is a document of the workspace's manifest, and the caller removes it once this has answered. Ordered that way deliberately - a folder the filesystem refuses is run_folder_not_removed with nothing changed, so the run stays in the trash and can be deleted again.
