优化更新代码，添加界面功能并整合

WPFluent/Services/IThemeService.cs

@@ -0,0 +1,55 @@
+
+
+
+using WPFluent.Appearance;
+
+namespace WPFluent;
+
+/// <summary>
+/// Represents a contract with a service that provides tools for manipulating the theme.
+/// </summary>
+public interface IThemeService
+{
+    /// <summary>
+    /// Gets current system theme.
+    /// </summary>
+    /// <returns>Currently set Windows theme using system enumeration.</returns>
+    SystemTheme GetNativeSystemTheme();
+
+    /// <summary>
+    /// Gets current system theme.
+    /// </summary>
+    /// <returns>Currently set Windows theme.</returns>
+    ApplicationTheme GetSystemTheme();
+
+    /// <summary>
+    /// Gets current application theme.
+    /// </summary>
+    /// <returns>Currently set application theme.</returns>
+    ApplicationTheme GetTheme();
+
+    /// <summary>
+    /// Sets current application accent.
+    /// </summary>
+    /// <returns><see langword="true"/> if the operation succeeds. <see langword="false"/> otherwise.</returns>
+    bool SetAccent(Color accentColor);
+
+    /// <summary>
+    /// Sets current application accent.
+    /// </summary>
+    /// <returns><see langword="true"/> if the operation succeeds. <see langword="false"/> otherwise.</returns>
+    bool SetAccent(SolidColorBrush accentSolidBrush);
+
+    /// <summary>
+    /// Sets currently used Windows OS accent.
+    /// </summary>
+    /// <returns><see langword="true"/> if the operation succeeds. <see langword="false"/> otherwise.</returns>
+    bool SetSystemAccent();
+
+    /// <summary>
+    /// Sets current application theme.
+    /// </summary>
+    /// <param name="applicationTheme">Theme type to set.</param>
+    /// <returns><see langword="true"/> if the operation succeeds. <see langword="false"/> otherwise.</returns>
+    bool SetTheme(ApplicationTheme applicationTheme);
+}