Queued runner jobs are automatically reaped when they become stale

Runner jobs that were stuck in the queued phase can no longer remain there indefinitely. The server now periodically reaps queued jobs that have been idle for more than one hour by cross-checking their real status with GitHub. If GitHub reports the job as completed, the dashboard is reconciled with the actual conclusion; if the job was pruned, it is marked complete. A 24-hour backstop also force-completes any job that still cannot be verified, so genuinely stale jobs clear automatically without blocking the runners view.