Batch Result Aggregator

Aggregate results from completed batches:

BATCH RESULTS:
[Results from all batches]

AGGREGATE:
{
  "combined_results": [...],  // All results merged
  "statistics": {
    "total_processed": number,
    "successful": number,
    "failed": number,
    "skipped": number
  },
  "aggregated_outputs": {
    // Combined/summarized outputs
  },
  "quality_metrics": {
    "average_score": number,
    "min_score": number,
    "max_score": number,
    "distribution": {...}
  },
  "failed_items": [
    {
      "item_id": "string",
      "error": "string",
      "batch_id": number
    }
  ]
}

POST-PROCESSING:
- Deduplication needed?
- Sorting/ordering?
- Final validation?