fix: 修复主题偶尔未正确初始化

Author: KiyanYang

src/DotVast.HashTool.WinUI/Services/Settings/AppearanceSettingsService.cs

@@ -23,7 +23,7 @@ public override async Task InitializeAsync()
             ? AppLanguage.System
             : WGAL.PrimaryLanguageOverride.ToAppLanguage();
 
-        SetTheme(); // 在初始化时就设置主题
+        await InitializeTheme();
         await Task.CompletedTask;
     }
 
@@ -78,6 +78,17 @@ private void SetTheme()
 
         TitleBarContextMenuHelper.UpdateTitleBarContextMenu(Theme);
     }
+    private async Task InitializeTheme()
+    {
+        if (App.MainWindow.Content is FrameworkElement rootElement)
+        {
+            while (!rootElement.IsLoaded)
+            {
+                await Task.Delay(25);
+            }
+        }
+        SetTheme();
+    }
     #endregion Theme
 
     #region Language