feat: add Activate command to ApplicationViewModel and bind to TrayIcon.

demo/Semi.Avalonia.Demo/App.axaml

@@ -33,6 +33,7 @@
             <TrayIcon
                 Icon="{OnPlatform Default=/Assets/irihi.ico, macOS=/Assets/irihi2.ico}"
                 MacOSProperties.IsTemplateIcon="true"
+                Command="{Binding ActivateCommand}"
                 ToolTipText="Semi Avalonia Demo">
                 <TrayIcon.Menu>
                     <NativeMenu>

demo/Semi.Avalonia.Demo/ViewModels/ApplicationViewModel.cs

@@ -1,4 +1,5 @@
 using Avalonia;
+using Avalonia.Controls;
 using Avalonia.Controls.ApplicationLifetimes;
 using CommunityToolkit.Mvvm.ComponentModel;
 using CommunityToolkit.Mvvm.Input;
@@ -8,9 +9,26 @@ namespace Semi.Avalonia.Demo.ViewModels;
 
 public partial class ApplicationViewModel : ObservableObject
 {
+    [RelayCommand]
+    private void Activate()
+    {
+        if (Application.Current?.ApplicationLifetime is not IClassicDesktopStyleApplicationLifetime desktop) return;
+        var mainWindow = desktop.MainWindow;
+        if (mainWindow is not null && !mainWindow.IsActive)
+        {
+            if (mainWindow.WindowState is WindowState.Minimized)
+            {
+                mainWindow.WindowState = WindowState.Normal;
+            }
+
+            mainWindow.Activate();
+        }
+    }
+
     [RelayCommand]
     private void JumpTo(string header)
     {
+        Activate();
         WeakReferenceMessenger.Default.Send(header, "JumpTo");
     }