chore(samples): settle samples left over by an aborted seed run #84

Problem

A seed run of the prepared samples (#71) that is aborted midway leaves a visible leftover: a sample in ERROR ("Das Beispiel konnte nicht vorbereitet werden …") or, after a hard kill, in NEW. The next run creates a fresh sample but the leftover stays in the list, and the UI cannot remove it (reject only from REVIEW; reprocessing a sample is refused on purpose, it would call the live model). Found in the re-review of #83.

Acceptance criteria

• pnpm seed:samples (or a separate operator step) settles leftover samples of the company that are not REVIEW, APPROVED or EXPORTED – e.g. rejects them with a fixed reason – through the status machine and with an audit event, never by deleting rows
• Tested: after an aborted run and a new run, the list shows no leftover sample in progress or in error
• Runbook §6 names the behaviour

Security/Privacy affected?

No – synthetic samples only.