Batch Checkpoint and Resume

Create checkpoint for batch process:

CURRENT STATE:
[Current processing state]

CHECKPOINT:
{
  "checkpoint_id": "uuid",
  "timestamp": "ISO date",
  "workflow_id": "string",
  "state": {
    "completed_batches": [1, 2, 3],
    "current_batch": 4,
    "current_item_index": 47,
    "failed_items": ["ids"],
    "accumulated_results": {...}
  },
  "resume_instructions": {
    "start_from_batch": 4,
    "start_from_item": 47,
    "skip_items": ["ids already processed"],
    "context_to_restore": {...}
  }
}

RESUME PROMPT:
When resuming from this checkpoint:
1. Load state from checkpoint
2. Skip already-processed items
3. Continue from [specific point]
4. Merge new results with accumulated results