curl --request POST \
  --url https://app.autoposting.ai/api-proxy/carousels/{id}/refine-design \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "instructions": "make the fonts larger and use a darker background"
}
'

{
  "success": true,
  "data": {
    "id": "car_01HXYZ",
    "brandSlug": "acme-corp",
    "title": "5 Growth Hacks for 2025",
    "slides": [
      {
        "id": "slide_01",
        "title": "Hook",
        "body": "Most founders ignore this...",
        "imageUrl": null,
        "order": 0
      }
    ],
    "design": null,
    "status": "draft",
    "createdAt": "2024-01-01T00:00:00Z",
    "updatedAt": "2024-01-01T00:00:00Z"
  }
}