[BE-053] Sweep: Implement retry backoff telemetry

[ONEONUORA]

Description\nAdd retry and backoff tracking for user sweep failures to avoid logs flood.\n\n## Files to Edit/Create\n- backend/src/services/sweep_worker.rs\n\n## Acceptance Criteria\n- Temporarily ignore users that throw errors during sweep executions.\n\n## Guidance / Hints\nRegister failure history inside database tables.