Stranded runner jobs are now automatically cleared from the queue

Runner jobs that get stuck in the queued phase no longer remain visible as queued indefinitely. The system now periodically reconciles these jobs against GitHub, marking missed or pruned jobs as completed, and applies a 24-hour backstop so any job that cannot be verified is force-completed with a stale conclusion. This keeps the Runners dashboard accurate and prevents phantom queued jobs from lingering for days.