Failed download jobs persist in BullMQ forever with no way to clear
them, leaving stale error notifications in Content Explorer and Easy
Setup. Adds a dismiss button (X) on failed download cards that removes
the job from the queue via a new DELETE endpoint.
- Backend: DELETE /api/downloads/jobs/:jobId endpoint
- Frontend: X button on failed download cards with immediate refresh
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
