returns 200 OK
page contains "Jobs" heading
page has Backfill and Live tabs
{'Backfill tab shows job table with columns': 'Job, Tags, Status, Pending, In Prog, Done, Failed, Skipped'}
{'action buttons visible': 'Pause, Retry Failed, Reprocess Stale'}
item detail section present with "Click a job row above" placeholder
logs clean - no ERROR or Traceback in recent logs
