优化更新代码，添加界面功能并整合

WPFluent/Markup/ThemesDictionary.cs

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+
+
+
+using WPFluent.Appearance;
+
+using System.Windows.Markup;
+
+namespace WPFluent.Markup;
+
+/// <summary>
+/// Provides a dictionary implementation that contains <c>WPF UI</c> theme resources used by components and other
+/// elements of a WPF application.
+/// </summary>
+/// <example>
+/// <code lang="xml"> /// &lt;Application ///     xmlns:ui="http://schemas.lepo.co/wpfui/2022/xaml"&gt; ///    
+/// &lt;Application.Resources&gt; ///         &lt;ResourceDictionary&gt; ///            
+/// &lt;ResourceDictionary.MergedDictionaries&gt; ///                 &lt;ui:ThemesDictionary Theme = "Dark" /&gt; ///  
+///           &lt;/ResourceDictionary.MergedDictionaries&gt; ///         &lt;/ResourceDictionary&gt; ///    
+/// &lt;/Application.Resources&gt; /// &lt;/Application&gt; ///</code>
+/// </example>
+[Localizability(LocalizationCategory.Ignore)]
+[Ambient]
+[UsableDuringInitialization(true)]
+public class ThemesDictionary : ResourceDictionary
+{
+    public ThemesDictionary() { SetSourceBasedOnSelectedTheme(ApplicationTheme.Light); }
+
+    private void SetSourceBasedOnSelectedTheme(ApplicationTheme? selectedApplicationTheme)
+    {
+        var themeName = selectedApplicationTheme switch
+        {
+            ApplicationTheme.Dark => "Dark",
+            ApplicationTheme.HighContrast => "HighContrast",
+            _ => "Light",
+        };
+
+        Source = new Uri($"{ApplicationThemeManager.ThemesDictionaryPath}{themeName}.xaml", UriKind.Absolute);
+    }
+
+    /// <summary>
+    /// Sets the default application theme.
+    /// </summary>
+    public ApplicationTheme Theme { set => SetSourceBasedOnSelectedTheme(value); }
+}