Cancel an active sweep through the engine's run and money policy.

The bernayser:write control call consumes no new quota. The engine cancels downstream runs, settles or releases their reservations, and transitions every nonterminal item. A foreign id is not_found and a terminal state yields validation_error. Fix the id or state before retrying; retry transient rate_limited or service_unavailable responses only after retry_after_sec. Requires the explicitly minted bernayser:write scope; bernayser:read permits safe projections and bernayser:write permits mutations. This BERNAYSER operation is quota-neutral. While dark it returns not_found, and a valid key without the required scope receives scope_missing. Fix a non-retryable request or credential before retrying; for rate_limited or service_unavailable, wait for retry_after_sec and retry once.