fix: reformat code / code improvements

lib/services/bar_tab_service.dart

@@ -5,6 +5,7 @@ import '../database/app_database.dart';
 import '../models/bar_tab.dart';
 import '../models/closed_tab.dart';
 import '../models/closed_tab_item.dart';
+import '../models/payment_method.dart';
 import '../models/product.dart';
 import '../models/tab_item.dart';
 
@@ -29,7 +30,7 @@ abstract class BarTabService {
 
   /// Archives the tab's current items into history and clears them.
   /// The tab itself stays open under the same customer name.
-  Future<void> closeTab(String tabId, {String paymentMethod = 'cash'});
+  Future<void> closeTab(String tabId, {PaymentMethod paymentMethod = PaymentMethod.cash});
 
   Future<List<ClosedTab>> getClosedTabs();
 
@@ -234,7 +235,7 @@ class DriftBarTabService implements BarTabService {
   }
 
   @override
-  Future<void> closeTab(String tabId, {String paymentMethod = 'cash'}) async {
+  Future<void> closeTab(String tabId, {PaymentMethod paymentMethod = PaymentMethod.cash}) async {
     await database.transaction(() async {
       final tabQuery = database.select(database.barTabs)
         ..where((tab) => tab.id.equals(tabId));
@@ -261,7 +262,7 @@ class DriftBarTabService implements BarTabService {
               originalTabId: tabId,
               customerName: tabRow.customerName,
               closedAt: DateTime.now(),
-              paymentMethod: Value(paymentMethod),
+              paymentMethod: Value(paymentMethod.value),
             ),
           );
 
@@ -326,7 +327,7 @@ class DriftBarTabService implements BarTabService {
           originalTabId: row.originalTabId,
           customerName: row.customerName,
           closedAt: row.closedAt,
-          paymentMethod: row.paymentMethod,
+          paymentMethod: PaymentMethod.fromValue(row.paymentMethod),
           items: itemRows.map<ClosedTabItem>(_mapClosedItemRow).toList(),
         ),
       );