List Merchants

{
  "success": true,
  "message": "Merchants retrieved successfully",
  "data": {
    "merchants": [
      {
        "id": 3,
        "marketplace_id": 1042,
        "merchant_id": 1676,
        "commission_rate": "0.0800",
        "status": "active",
        "invite_token": null,
        "invited_at": null,
        "joined_at": "2026-03-28T11:33:21.646Z",
        "created_at": "2026-03-28T11:33:21.646Z",
        "updated_at": "2026-03-28T11:33:21.646Z",
        "merchant": {
          "id": 1676,
          "business_email": "merchant@example.com"
        }
      }
    ],
    "pagination": {
      "page": 1,
      "limit": 20,
      "total": 1,
      "pages": 1
    }
  }
}