!1 Invalid quantity is rejected as a business input

Quantity must be positive. Zero is a valid integer input but not a valid
order quantity, so the fixture reports a business rejection rather than a
conversion exception.

|script|Order workflow|
|$order=|create order for|C-100|
|check|add item|COFFEE|quantity|0|to order|$order|false|
|check|last error?|Quantity must be a positive whole number.|
|check|status of order|$order|draft|
