Add brightness/contrast sliders, input source switching, and 9-language localization

- Add VCP commands for brightness (10), contrast (12), input source (60)
- Fix UTF-16 encoding for monitor data parsing
- Add system tray app with monitor controls
- Add localization for en, es, fr, de, zh, ja, pt, it, hi
- Update to .NET 9.0
- Add LICENSE and README

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

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

DellMonitorControl/App.xaml.cs

@@ -1,17 +1,39 @@
-using System;
-using System.Collections.Generic;
-using System.Configuration;
-using System.Data;
-using System.Linq;
-using System.Threading.Tasks;
+using Hardcodet.Wpf.TaskbarNotification;
 using System.Windows;
 
 namespace DellMonitorControl
 {
-    /// <summary>
-    /// Interaction logic for App.xaml
-    /// </summary>
     public partial class App : Application
     {
+        private TaskbarIcon? _trayIcon;
+        private MainWindow? _mainWindow;
+
+        private void Application_Startup(object sender, StartupEventArgs e)
+        {
+            _trayIcon = (TaskbarIcon)FindResource("TrayIcon");
+            _trayIcon.TrayLeftMouseUp += TrayIcon_Click;
+
+            _mainWindow = new MainWindow();
+            _mainWindow.Show();
+        }
+
+        private void TrayIcon_Click(object sender, RoutedEventArgs e)
+        {
+            if (_mainWindow == null) return;
+
+            if (_mainWindow.IsVisible)
+                _mainWindow.Hide();
+            else
+            {
+                _mainWindow.Show();
+                _mainWindow.Activate();
+            }
+        }
+
+        protected override void OnExit(ExitEventArgs e)
+        {
+            _trayIcon?.Dispose();
+            base.OnExit(e);
+        }
     }
 }