curl --request POST \
  --url https://app.solya.app/api/markdown-plans/{planId}/items \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "discountPercent": 30,
  "shopId": "shop-uuid-paris-opera",
  "sizeId": "sz-uuid-001",
  "variantId": "var-uuid-001"
}
'

{
  "itemId": "mdi-uuid-002",
  "message": "Item added successfully",
  "success": true,
  "warnings": [
    {
      "message": "Discount is below the recommended minimum of 20% for this category",
      "ruleId": "MIN_MARKDOWN_RATE"
    }
  ]
}