feat(configmanager): complete service registrations in App.axaml.cs

Add IDialogService registration using factory pattern for window access.
Add GetMainWindow helper method to provide window reference for dialogs.

NEW/src/Utils/JdeScoping.ConfigManager/App.axaml.cs

@@ -1,4 +1,5 @@
 using Avalonia;
+using Avalonia.Controls;
 using Avalonia.Controls.ApplicationLifetimes;
 using Avalonia.Markup.Xaml;
 using JdeScoping.ConfigManager.Services;
@@ -15,17 +16,13 @@ public partial class App : Application
     /// </summary>
     public static IServiceProvider Services { get; private set; } = null!;
 
-    /// <summary>
-    /// Initializes the Avalonia XAML loader.
-    /// </summary>
+    /// <inheritdoc />
     public override void Initialize()
     {
         AvaloniaXamlLoader.Load(this);
     }
 
-    /// <summary>
-    /// Called when the framework initialization is complete; configures services and sets the main window.
-    /// </summary>
+    /// <inheritdoc />
     public override void OnFrameworkInitializationCompleted()
     {
         var services = new ServiceCollection();
@@ -60,7 +57,16 @@ public partial class App : Application
         services.AddSingleton<IValidationService, ValidationService>();
         services.AddScoped<IConfigFileService, ConfigFileService>();
 
+        // Platform Services
+        services.AddSingleton<IDialogService>(sp =>
+            new AvaloniaDialogService(GetMainWindow));
+
         // ViewModels
         services.AddTransient<MainWindowViewModel>();
     }
+
+    private Window? GetMainWindow()
+    {
+        return (ApplicationLifetime as IClassicDesktopStyleApplicationLifetime)?.MainWindow;
+    }
 }