Initial samples: TodoApp and ShellDemo

Two sample applications demonstrating OpenMaui Linux:

TodoApp:
- Full task manager with NavigationPage
- CollectionView with XAML data binding
- DisplayAlert dialogs
- Grid layouts with star sizing

ShellDemo:
- Comprehensive control showcase
- Shell with flyout navigation
- All core MAUI controls demonstrated
- Real-time event logging

Both samples reference OpenMaui.Controls.Linux via NuGet.

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

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

ShellDemo/MauiProgram.cs

@@ -0,0 +1,24 @@
+// MauiProgram.cs - Shared MAUI app configuration
+// Works across all platforms (iOS, Android, Windows, Linux)
+
+using Microsoft.Maui.Hosting;
+using Microsoft.Maui.Platform.Linux.Hosting;
+
+namespace ShellDemo;
+
+public static class MauiProgram
+{
+    public static MauiApp CreateMauiApp()
+    {
+        var builder = MauiApp.CreateBuilder();
+        
+        // Configure the app (shared across all platforms)
+        builder.UseMauiApp<App>();
+        
+        // Add Linux platform support
+        // On other platforms, this would be iOS/Android/Windows specific
+        builder.UseLinux();
+        
+        return builder.Build();
+    }
+}