List groups

curl --request GET \
  --url https://api.shoppex.io/dev/v1/groups \
  --header 'Authorization: Bearer <token>'

{
  "data": [
    {
      "id": "grp_db_1",
      "uniqid": "grp_1",
      "shop_id": "shop_1",
      "title": "VIP Access",
      "description": "Priority products for members",
      "is_unlisted": false,
      "sort_order": 1,
      "created_at": 1711962000,
      "updated_at": 1711965600,
      "products_bound": [
        {
          "uniqid": "prod_starter",
          "title": "Starter Pack",
          "type": "DIGITAL",
          "price": 29.99,
          "price_display": 29.99,
          "currency": "USD",
          "stock": 999,
          "custom_fields": {
            "badge": "vip"
          }
        }
      ]
    }
  ],
  "pagination": {
    "next_cursor": null,
    "has_more": false
  }
}