fix: eliminate black-square flash on startup, start cleanly in tray

MoneyShot/App.xaml

@@ -2,7 +2,7 @@
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:local="clr-namespace:MoneyShot"
-             StartupUri="MainWindow.xaml">
+             ShutdownMode="OnExplicitShutdown">
     <Application.Resources>
         <ResourceDictionary>
             <ResourceDictionary.MergedDictionaries>

MoneyShot/App.xaml.cs

@@ -32,6 +32,14 @@ protected override void OnStartup(StartupEventArgs e)
         }
 
         base.OnStartup(e);
+
+        // StartupUri is intentionally not used. It calls Show() during startup, which paints an
+        // unrendered (black) frame before the Loaded handler can hide it when StartInTray is set.
+        // Instead we create the window here and let InitializeApplication decide whether to show
+        // it or just realize its handle for hotkeys — see MainWindow.InitializeApplication.
+        var mainWindow = new MainWindow();
+        MainWindow = mainWindow;
+        mainWindow.InitializeApplication();
     }
 
     protected override void OnExit(ExitEventArgs e)

MoneyShot/MainWindow.xaml.cs

@@ -3,6 +3,7 @@
 using System.Windows.Controls;
 using System.Windows.Forms;
 using System.Windows.Input;
+using System.Windows.Interop;
 using System.Windows.Media;
 using MoneyShot.Services;
 using MoneyShot.Views;
@@ -37,27 +38,40 @@ public MainWindow()
         _historyService = new HistoryService();
 
         SetupSystemTray();
-        Loaded += MainWindow_Loaded;
     }
 
-    private async void MainWindow_Loaded(object sender, RoutedEventArgs e)
+    /// <summary>
+    /// Performs post-construction startup: realizes the native handle, binds global hotkeys, and
+    /// shows the window only when the user hasn't opted to start in the tray. Called once from
+    /// <see cref="App.OnStartup"/>. When <see cref="Models.AppSettings.StartInTray"/> is set the
+    /// window is never shown — <see cref="WindowInteropHelper.EnsureHandle"/> creates the HWND that
+    /// hotkey registration needs without painting anything, which avoids the black-frame flash that
+    /// Show()-then-Hide() produced.
+    /// </summary>
+    public void InitializeApplication()
     {
         try
         {
-            _hotKeyService.Initialize(this);
-            RegisterHotKeys();
-            PopulateMonitorButtons();
-
-            // Check if app should start in tray
             var settings = _settingsService.LoadSettings();
+
             if (settings.StartInTray)
             {
-                Hide();
+                // Realize the Win32 handle without making the window visible.
+                new WindowInteropHelper(this).EnsureHandle();
+            }
+            else
+            {
+                ShowMainWindow();
             }
 
+            // The HWND now exists (via EnsureHandle or Show), so global hotkeys can bind to it.
+            _hotKeyService.Initialize(this);
+            RegisterHotKeys();
+            PopulateMonitorButtons();
+
             if (settings.CheckForUpdatesOnStartup)
             {
-                await CheckForUpdatesOnStartupAsync();
+                _ = CheckForUpdatesOnStartupAsync();
             }
         }
         catch (Exception ex)