fix: reformat code / code improvements

lib/views/dialogs/close_tab_dialog.dart

@@ -2,6 +2,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_svg/svg.dart';
 import 'package:provider/provider.dart';
 
+import '../../models/payment_method.dart';
 import '../../viewmodels/bar_screen_view_model.dart';
 import '../widgets/slide_confirm.dart';
 
@@ -11,7 +12,7 @@ Future<void> confirmCloseTab(BuildContext context) async {
 
   if (tab == null) return;
 
-  String paymentMethod = 'cash';
+  PaymentMethod paymentMethod = PaymentMethod.cash;
 
   final confirmed = await showDialog<bool>(
     context: context,
@@ -66,8 +67,8 @@ Future<void> confirmCloseTab(BuildContext context) async {
 }
 
 class _PaymentPicker extends StatelessWidget {
-  final String selected;
-  final ValueChanged<String> onChanged;
+  final PaymentMethod selected;
+  final ValueChanged<PaymentMethod> onChanged;
 
   const _PaymentPicker({
     required this.selected,
@@ -75,8 +76,8 @@ class _PaymentPicker extends StatelessWidget {
   });
 
   static const _options = [
-    ('cash', 'Cash'),
-    ('payconiq', 'Payconiq'),
+    (PaymentMethod.cash, 'Cash'),
+    (PaymentMethod.payconiq, 'Payconiq'),
   ];
 
   @override
@@ -96,7 +97,7 @@ class _PaymentPicker extends StatelessWidget {
             label: Row(
               mainAxisSize: MainAxisSize.min,
               children: [
-                if (value == 'cash')
+                if (value == PaymentMethod.cash)
                   const Icon(
                     Icons.attach_money,
                     size: 16,