feat(app): 初始化本地通知桌面应用

搭建 .NET 8 WPF 应用骨架，加入系统托盘、单实例启动与主控制面板。
实现本地 HTTP /notify 消息接入、频道严格匹配、免打扰、熔断限流与历史持久化。
补充弹窗样式配置、队列/推挤/替换展示、溢出处理、应用图标和项目文档。

Initial-Commit: true

App.xaml.cs

@@ -0,0 +1,152 @@
+using System.IO;
+using System.Threading;
+using System.Windows;
+using Forms = System.Windows.Forms;
+
+namespace OmniNotify;
+
+public partial class App : System.Windows.Application
+{
+    private const string SingleInstanceMutexName = @"Local\OmniNotify.SingleInstance";
+    private const string ActivateEventName = @"Local\OmniNotify.Activate";
+    private Forms.NotifyIcon? _notifyIcon;
+    private AppStore? _store;
+    private LocalHttpServer? _server;
+    private Mutex? _singleInstanceMutex;
+    private bool _ownsSingleInstanceMutex;
+    private EventWaitHandle? _activateEvent;
+    private RegisteredWaitHandle? _activateWait;
+
+    public AppState State { get; private set; } = new();
+    public NotificationRouter Router { get; private set; } = null!;
+    public PopupCoordinator PopupCoordinator { get; private set; } = null!;
+    public string ListenUrl => _server?.Url ?? "";
+    public string? ServerError => _server?.LastError;
+
+    protected override void OnStartup(StartupEventArgs e)
+    {
+        _singleInstanceMutex = new Mutex(true, SingleInstanceMutexName, out var createdNew);
+        _ownsSingleInstanceMutex = createdNew;
+        _activateEvent = new EventWaitHandle(false, EventResetMode.AutoReset, ActivateEventName);
+        if (!createdNew)
+        {
+            _activateEvent.Set();
+            Shutdown();
+            return;
+        }
+
+        RegisterActivationListener();
+        base.OnStartup(e);
+
+        _store = new AppStore();
+        State = _store.Load();
+        PopupCoordinator = new PopupCoordinator();
+        Router = new NotificationRouter(State, _store, PopupCoordinator);
+        Router.StateChanged += UpdateTrayMenu;
+
+        _server = new LocalHttpServer(Router);
+        _server.Start(State.Settings.LocalPort);
+
+        CreateTrayIcon();
+        ShowMainWindow();
+    }
+
+    public void SaveState()
+    {
+        _store?.Save(State);
+        UpdateTrayMenu();
+    }
+
+    public void ShowMainWindow()
+    {
+        if (MainWindow is null)
+        {
+            MainWindow = new MainWindow();
+        }
+
+        MainWindow.Show();
+        MainWindow.WindowState = WindowState.Normal;
+        MainWindow.Activate();
+    }
+
+    private void RegisterActivationListener()
+    {
+        if (_activateEvent is null)
+        {
+            return;
+        }
+
+        _activateWait = ThreadPool.RegisterWaitForSingleObject(
+            _activateEvent,
+            (_, _) => Dispatcher.Invoke(ShowMainWindow),
+            null,
+            Timeout.InfiniteTimeSpan,
+            false);
+    }
+
+    private void CreateTrayIcon()
+    {
+        var iconPath = Path.Combine(AppContext.BaseDirectory, "app.ico");
+        _notifyIcon = new Forms.NotifyIcon
+        {
+            Icon = new System.Drawing.Icon(iconPath),
+            Text = "Omni-Notify",
+            Visible = true
+        };
+        _notifyIcon.MouseClick += (_, args) =>
+        {
+            if (args.Button == Forms.MouseButtons.Left)
+            {
+                Dispatcher.Invoke(ShowMainWindow);
+            }
+        };
+        UpdateTrayMenu();
+    }
+
+    private void UpdateTrayMenu()
+    {
+        if (_notifyIcon is null)
+        {
+            return;
+        }
+
+        var menu = new Forms.ContextMenuStrip();
+        menu.Items.Add("打开主控制面板", null, (_, _) => Dispatcher.Invoke(ShowMainWindow));
+        menu.Items.Add("全局设置", null, (_, _) => Dispatcher.Invoke(() =>
+        {
+            ShowMainWindow();
+            if (MainWindow is MainWindow window)
+            {
+                window.FocusSettingsTab();
+            }
+        }));
+        menu.Items.Add(State.Settings.DndEnabled ? "关闭免打扰" : "开启免打扰", null, (_, _) => Dispatcher.Invoke(() =>
+        {
+            State.Settings.DndEnabled = !State.Settings.DndEnabled;
+            SaveState();
+        }));
+
+        var resetBreaker = menu.Items.Add("解除熔断", null, (_, _) => Dispatcher.Invoke(() => Router.ResetCircuitBreaker()));
+        resetBreaker.Enabled = State.Settings.CircuitBreakerOpen;
+        resetBreaker.ForeColor = State.Settings.CircuitBreakerOpen ? System.Drawing.Color.Firebrick : System.Drawing.SystemColors.ControlText;
+
+        menu.Items.Add(new Forms.ToolStripSeparator());
+        menu.Items.Add("退出软件", null, (_, _) => Dispatcher.Invoke(Shutdown));
+        _notifyIcon.ContextMenuStrip = menu;
+    }
+
+    protected override void OnExit(ExitEventArgs e)
+    {
+        _activateWait?.Unregister(null);
+        _activateEvent?.Dispose();
+        if (_ownsSingleInstanceMutex)
+        {
+            _singleInstanceMutex?.ReleaseMutex();
+        }
+        _singleInstanceMutex?.Dispose();
+        _notifyIcon?.Dispose();
+        _server?.Dispose();
+        _store?.Save(State);
+        base.OnExit(e);
+    }
+}