Create spend

curl --request POST \
  --url https://api.rampartcorporation.com/developer/v1/spends \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'x-account-token: <x-account-token>' \
  --data '{
  "vendorName": "Office Supplies Co.",
  "spends": [
    {
      "quantity": 5,
      "unitPrice": 10.99,
      "name": "Paper Clips",
      "itemId": "ITEM-123",
      "purchaseDate": "2023-01-15T14:30:00Z",
      "uom": "box"
    }
  ]
}'

{
  "success": true,
  "data": [
    {
      "name": "Printer Ink Cartridge",
      "normalizedItemId": "INK-123",
      "unitPrice": 45.99,
      "quantity": 2,
      "savingsRealized": 10.5
    }
  ]
}