GET /api/v1/sub-merchant

{
  "success": true,
  "data": [
    {
      "subMerchantId": "sm-7f4a9940c621",
      "name": "My Store",
      "commercialName": "My Store SN",
      "countries": ["SN", "CI"],
      "isActive": true,
      "isDefault": true,
      "CREATED_AT": "2026-03-15T03:47:32.000Z"
    }
  ],
  "total": 1,
  "page": 1,
  "totalPages": 1
}