Add admin transaction cancellation without deleting history.

Cancelled transactions are excluded from paid totals and due-date
calculations while remaining visible for audit purposes.

utils/paymentAmount.js

@@ -24,13 +24,18 @@ const sanitizeNotes = (notes) => {
 
 const rialsToToman = (value) => Math.floor(toNonNegativeNumber(value) / 10);
 
+const isCancelledTransaction = (trx = {}) => String(trx.status || '').toLowerCase() === 'cancelled';
+
 const isPaidTransaction = (trx = {}) => {
+  if (isCancelledTransaction(trx)) return false;
   const status = String(trx.status || '').toLowerCase();
   if (status === 'pending') return false;
   if (status === 'paid') return true;
   return Boolean(trx.date);
 };
 
+const isActiveTransaction = (trx = {}) => !isCancelledTransaction(trx);
+
 const sumPaidTransactions = (transactions = []) => {
   if (!Array.isArray(transactions)) return 0;
   return transactions.reduce((sum, trx) => {
@@ -50,6 +55,8 @@ module.exports = {
   sanitizeNotes,
   rialsToToman,
   isPaidTransaction,
+  isCancelledTransaction,
+  isActiveTransaction,
   sumPaidTransactions,
   remainingPayable
 };