Добавьте файлы проекта.

BookReader/AppShell.xaml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<Shell xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+       xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+       xmlns:views="clr-namespace:BookReader.Views"
+       x:Class="BookReader.AppShell"
+       Shell.FlyoutBehavior="Disabled"
+       Shell.BackgroundColor="#3E2723"
+       Shell.ForegroundColor="White"
+       Shell.TitleColor="White">
+
+    <ShellContent
+        Title="Library"
+        ContentTemplate="{DataTemplate views:BookshelfPage}"
+        Route="bookshelf" />
+
+</Shell>