fix: format prices in notifications, change partial payment label, and add session holding notify API

utils/paymentAmount.test.js

@@ -10,7 +10,8 @@ const {
   rialsToToman,
   isPaidTransaction,
   sumPaidTransactions,
-  remainingPayable
+  remainingPayable,
+  formatPrice
 } = require('./paymentAmount');
 
 describe('payment amount helpers', () => {
@@ -40,6 +41,17 @@ describe('payment amount helpers', () => {
   });
 });
 
+describe('formatPrice', () => {
+  it('formats numbers and numeric strings with decimal thousand separators', () => {
+    assert.equal(formatPrice(8000000), '8,000,000');
+    assert.equal(formatPrice('8000000'), '8,000,000');
+    assert.equal(formatPrice(500000), '500,000');
+    assert.equal(formatPrice(0), '0');
+    assert.equal(formatPrice(''), '');
+    assert.equal(formatPrice(null), '');
+  });
+});
+
 describe('rialsToToman', () => {
   it('drops one zero so spreadsheet Rials become website Toman', () => {
     assert.equal(rialsToToman(110_000_000), 11_000_000);