feat(app): 初始化自动关机工具首个版本

实现基于 WPF 的 AutoShutdown 主界面，支持关机、重启、睡眠、休眠、唤醒、锁屏和注销等电源任务。

支持指定时间和倒计时计划、执行前提醒、系统关机撤销、Windows 唤醒任务、托盘运行、自定义图标以及 OmniNotify 通知适配。

修复关闭到托盘时的运行提醒，并支持单击托盘图标打开或收起主界面。

补充 README、发布配置和 win-x64 Release 输出要求。

Release: win-x64

Services/ScreenshotService.cs

@@ -0,0 +1,33 @@
+#if DEBUG
+using System.IO;
+using System.Windows;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+
+namespace AutoShutdown.Services;
+
+internal static class ScreenshotService
+{
+    public static string Capture(Window window, string? requestedPath = null)
+    {
+        var path = string.IsNullOrWhiteSpace(requestedPath)
+            ? Path.Combine(AppContext.BaseDirectory, "Screenshots", $"ui-{DateTime.Now:yyyyMMdd-HHmmss}.png")
+            : Path.GetFullPath(requestedPath);
+
+        var directory = Path.GetDirectoryName(path) ?? AppContext.BaseDirectory;
+        Directory.CreateDirectory(directory);
+
+        var visual = (FrameworkElement)window.Content;
+        var width = Math.Max(1, (int)Math.Ceiling(visual.ActualWidth));
+        var height = Math.Max(1, (int)Math.Ceiling(visual.ActualHeight));
+        var target = new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Pbgra32);
+        target.Render(visual);
+
+        var encoder = new PngBitmapEncoder();
+        encoder.Frames.Add(BitmapFrame.Create(target));
+        using var stream = File.Create(path);
+        encoder.Save(stream);
+        return path;
+    }
+}
+#endif