Add auto-update check and DDC/CI timeout fix

- Auto-update checker on startup via Gitea API
- Balloon notification when update available, click to download
- 5-second timeout on DDC/CI commands to prevent hangs
- Simplified version scheme to match release tags
- Workflow auto-updates version in csproj from tag

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

DellMonitorControl/App.xaml.cs

@@ -7,13 +7,42 @@ namespace DellMonitorControl
     {
         private TaskbarIcon? _trayIcon;
         private MainWindow? _mainWindow;
+        private UpdateInfo? _pendingUpdate;
 
-        private void Application_Startup(object sender, StartupEventArgs e)
+        private async void Application_Startup(object sender, StartupEventArgs e)
         {
             _trayIcon = (TaskbarIcon)FindResource("TrayIcon");
             _trayIcon.TrayLeftMouseUp += TrayIcon_Click;
+            _trayIcon.TrayBalloonTipClicked += TrayIcon_BalloonTipClicked;
 
             _mainWindow = new MainWindow();
+
+            // Check for updates in background
+            await CheckForUpdatesAsync();
+        }
+
+        private async System.Threading.Tasks.Task CheckForUpdatesAsync()
+        {
+            try
+            {
+                _pendingUpdate = await UpdateChecker.CheckForUpdateAsync();
+                if (_pendingUpdate != null && _trayIcon != null)
+                {
+                    _trayIcon.ShowBalloonTip(
+                        "Update Available",
+                        $"Monitor Control v{_pendingUpdate.LatestVersion} is available.\nClick to download.",
+                        BalloonIcon.Info);
+                }
+            }
+            catch { }
+        }
+
+        private void TrayIcon_BalloonTipClicked(object sender, RoutedEventArgs e)
+        {
+            if (_pendingUpdate != null && !string.IsNullOrEmpty(_pendingUpdate.DownloadUrl))
+            {
+                UpdateChecker.OpenDownloadPage(_pendingUpdate.DownloadUrl);
+            }
         }
 
         private async void TrayIcon_Click(object sender, RoutedEventArgs e)