Use multibinding for receipt date format

src/Helpers/DateFormatConverter.cs

@@ -0,0 +1,27 @@
+
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using Avalonia.Data.Converters;
+
+namespace MayShow.Helpers;
+
+public class DateFormatConverter : IMultiValueConverter
+{
+    public object? Convert(
+        IList<object?> values,
+        Type targetType,
+        object? parameter,
+        CultureInfo culture)
+    {
+        if (values.Count >= 2 && values[0] is DateOnly date && values[1] is string format)
+        {
+            return date.ToString(format);
+        }
+        if (values.Count >= 2 && values[0] is string dateFormat && values[1] is DateOnly dateOnly)
+        {
+            return dateOnly.ToString(dateFormat);
+        }
+        return 0.0;
+    }
+}