Добавьте файлы проекта.

BookReader/App.xaml.cs

@@ -0,0 +1,19 @@
+using BookReader.Services;
+
+namespace BookReader;
+
+public partial class App : Application
+{
+    public App(IDatabaseService databaseService)
+    {
+        InitializeComponent();
+
+        // Initialize database
+        Task.Run(async () => await databaseService.InitializeAsync()).Wait();
+    }
+
+    protected override Window CreateWindow(IActivationState? activationState)
+    {
+        return new Window(new AppShell());
+    }
+}