Canteen Management

A completed sale can be voided only by a second person.

• A cashier requests the void with a reason; a manager approves or rejects.
• The requester and the cashier who rang the sale cannot approve: 403 SelfApprovalForbidden.
• Same business day only; a sale on a closed day cannot be voided.
• Approving an employee sale gives the month back exactly what the sale took (gross, subsidy and subsidised units) in the same transaction, under the sale and account locks.
• A voided sale keeps its bill number.
• Audit entries for request, approve and reject.
• Manager list of pending void requests.

Built and tested on integration/canteen-v1; merge to dev pending.