Tests: add flutter_test and money formatting tests

The template counter test could never compile (no flutter_test dev
dependency, no MyApp). Replace it with unit tests for formatMoney
(INR byte-identical to the old formatter, AED, BHD) and currency parsing.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

test/money_test.dart

@@ -0,0 +1,42 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:intl/intl.dart';
+import 'package:scalar_attendance/api_service.dart';
+import 'package:scalar_attendance/money.dart';
+
+void main() {
+  // The formatter the payslips screen used before org currencies.
+  String legacyInr(num v) => '₹${NumberFormat('#,##,###').format(v)}';
+
+  group('formatMoney', () {
+    test('missing / INR currency is byte-identical to the old rupee output', () {
+      for (final v in [0, 7, 999, 1000, 54321, 123456.7, 1234567, 98765432.49]) {
+        expect(formatMoney(v), legacyInr(v));
+        expect(formatMoney(v, null), legacyInr(v));
+        expect(formatMoney(v, ''), legacyInr(v));
+        expect(formatMoney(v, 'INR'), legacyInr(v));
+        expect(formatMoney(v, 'inr'), legacyInr(v));
+      }
+      expect(formatMoney(1234567), '₹12,34,567');
+    });
+
+    test('AED uses the ISO code, western grouping and 2 decimals', () {
+      expect(formatMoney(12345.5, 'AED'), 'AED 12,345.50');
+      expect(formatMoney(0, 'AED'), 'AED 0.00');
+    });
+
+    test('BHD uses 3 decimals', () {
+      expect(formatMoney(1234.5, 'BHD'), 'BHD 1,234.500');
+    });
+  });
+
+  group('payslip / profile currency', () {
+    test('parsed when present, null on older servers', () {
+      final withCur = Payslip.fromJson({'gid': 'p1', 'netPay': 10, 'currency': 'AED'});
+      final without = Payslip.fromJson({'gid': 'p1', 'netPay': 10});
+      expect(withCur.currency, 'AED');
+      expect(without.currency, isNull);
+      expect(Profile.fromJson({'currency': 'SAR'}).currency, 'SAR');
+      expect(Profile.fromJson({}).currency, isNull);
+    });
+  });
+}