Test repositories from experiment runs get a cleanup rule and a script

Each experiment run of Satsuma's autonomous system creates its own private code repositories for the products it builds. A session in the system took stock of them: seven repositories, created by the first three runs, all test artefacts. "None of these are production." Every run starts two fresh local chains, so the contracts those repositories describe no longer exist anywhere.

A cleanup script landed. It deletes a run's repositories by their name suffix and does a dry run first. The dry run confirmed the same seven targets.

The rule is now written down: per-run repositories are test artefacts, deleted by hand once the run is archived, and the archive is the record. A fourth run is still building, and its repositories follow the same route once it is archived.

The seven have not been deleted. An automated safeguard blocked the deletion as irreversible, so the commands were handed to the operator to run by hand.