curl --request POST \
  --url https://api.topcalls.ai/v1/leads/bulk \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "list_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "leads": [
    {
      "phone_number": "<string>",
      "name": "",
      "email": "jsmith@example.com",
      "notes": "<string>",
      "tags": [],
      "metadata": {}
    }
  ],
  "mode": "merge"
}
'

{
  "success": true,
  "inserted": 123,
  "updated": 123,
  "duplicates": 123,
  "total_processed": 123,
  "duration_ms": 123
}