feat: Avalonia 常驻通知应用（保活 + 弹窗 + 跨桌面）

- 常驻 Host：无主窗口保活 + 系统托盘菜单
- Toast 弹窗：堆叠 / 自动消失 / 悬停暂停 / 淡入淡出 / 点击关闭
- Sticky 常驻弹窗与 InputMode 边框配色
- 跨虚拟桌面显示（源生成 COM PinView，AOT 友好）
- 设置窗口（Semi + Ursa）+ JSON 源生成持久化
- AOT 准备：IsAotCompatible 0 警告

Notify/Program.cs

@@ -0,0 +1,21 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+
+namespace Notify;
+
+internal static class Program
+{
+    // Avalonia configuration, don't remove; also used by the visual designer.
+    public static AppBuilder BuildAvaloniaApp() =>
+        AppBuilder.Configure<App>()
+            .UsePlatformDetect()
+            .WithInterFont()
+            .LogToTrace();
+
+    [STAThread]
+    public static void Main(string[] args) =>
+        BuildAvaloniaApp()
+            // OnExplicitShutdown = 持续保活：没有主窗口也不会退出，只有显式 Shutdown 才结束
+            .StartWithClassicDesktopLifetime(args, ShutdownMode.OnExplicitShutdown);
+}