fix: обновить использование FToast на showFToast в expenses_screen

finance_app/lib/screens/expenses_screen.dart

@@ -103,17 +103,23 @@ class _ExpensesScreenState extends State<ExpensesScreen> with TickerProviderStat
     try {
       await _controller.addSampleTransaction();
       if (mounted) {
-        FToast.of(context).show(
-          title: const Text('Success'),
-          subtitle: const Text('Transaction added successfully'),
+        showFToast(
+          context: context,
+          builder: (context) => const FToast(
+            title: Text('Success'),
+            description: Text('Transaction added successfully'),
+          ),
         );
       }
     } catch (e) {
       if (mounted) {
-        FToast.of(context).show(
-          title: const Text('Error'),
-          subtitle: Text('Error adding transaction: $e'),
-          style: FToastStyle.destructive,
+        showFToast(
+          context: context,
+          builder: (context) => FToast(
+            title: const Text('Error'),
+            description: Text('Error adding transaction: $e'),
+            style: FToastStyle.destructive,
+          ),
         );
       }
     }