0d5982d910
_readiness_work_counts()'s active_api_runs set is {"queued", "running",
"waiting_for_approval"} — it excludes "stopping", the status
_handle_stop_run() sets while a run is being interrupted. Since the stop
is fully cooperative (the run stays "stopping" — doing real
executor-thread work — until the agent actually notices the interrupt and
the task settles to "cancelled", an unbounded window, not a fixed
timeout), /health/detailed's background_queues.active_api_runs
undercounts real active work for that whole duration.
Fix: add "stopping" to the active-status set. background_queues.status
itself is hardcoded "ok" (gateway/readiness.py), so this doesn't change
overall readiness — it only corrects the count value external monitoring
tooling reads from this endpoint.