优化更新代码，添加界面功能并整合

WPFluent/Converters/FallbackBrushConverter.cs

@@ -0,0 +1,22 @@
+
+
+
+using System.Windows.Data;
+
+namespace WPFluent.Converters;
+
+internal class FallbackBrushConverter : IValueConverter
+{
+    public object Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
+    {
+        return value switch
+        {
+            SolidColorBrush brush => brush,
+            Color color => new SolidColorBrush(color),
+            _ => new SolidColorBrush(Colors.Red),
+        };
+    }
+
+    public object ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
+    { throw new NotImplementedException(); }
+}