Procurement: add one-off items to an order after the quote has been signed

What: Allow adding one-off / custom items to a procurement order after the quote has been won and signed.

Current behavior: Order lines are created exclusively from won-quote lines — there is no way to append an extra item (e.g. a cable, license, or last-minute addition) to the order afterwards; it has to be handled outside Salesbuildr or by amending the quote.

Desired behavior: From the order/procurement view, add an ad-hoc line item (product search or free-form one-off) to an existing order created from a won quote.

Note: recreated after accidental deletion — originally filed 2026-07-08.