The non-quiet one-shot path exited 0 unless a Kanban worker was running, so
scripts could not tell a failed `hermes chat -q` from a good one and an
incomplete turn (partial, iteration budget) still read as success (#111770).
Both one-shot paths now share one contract: 0 completed, 1 failed / partial /
incomplete / never ran, 130 interrupted. The Kanban EX_TEMPFAIL sentinel also
fires for `upstream_rate_limit` (aggregator's upstream 429) and `overloaded`
(503/529): neither says anything about the task, so the dispatcher should
requeue without a failure tick rather than count it toward the breaker.
23863ccbaf