Code review cleanup: dead code, unused capability, accessibility gap

- Remove unused `using Microsoft.Win32;` from MainPage.xaml.cs (leftover
  from the WPF OpenFileDialog era; WinUI uses Windows.Storage.Pickers)
- Trim App.xaml.cs down to the two usings it actually needs instead of the
  full WinUI3 template boilerplate list
- Change App.MainWindowInstance to an internal setter (only MainWindow
  itself should assign it)
- Add AutomationProperties.Name to the icon-only Settings button so screen
  readers announce it (it only had a mouse tooltip before)
- Delete Assets/AppIcon.ico: unreferenced by both the manifest and code,
  the real app icon comes from ApplicationIcon (branding/AmiReel.ico) and
  AppWindow.SetIcon at runtime
- Drop the systemAIModels capability from Package.appxmanifest; the app
  doesn't call any Windows AI API, so declaring it is an unnecessary
  privilege request

Verified: dotnet build produces 0 warnings/errors, app launches unchanged.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

AmiReel.csproj

@@ -27,7 +27,6 @@
     <Content Include="Assets\Square44x44Logo.targetsize-24_altform-unplated.png" />
     <Content Include="Assets\Square44x44Logo.targetsize-48_altform-lightunplated.png" />
     <Content Include="Assets\StoreLogo.png" />
-    <Content Include="Assets\AppIcon.ico" />
     <Content Include="Assets\Wide310x150Logo.scale-200.png" />
   </ItemGroup>
 

App.xaml.cs

@@ -1,20 +1,6 @@
-using Windows.ApplicationModel;
-using Windows.ApplicationModel.Activation;
-using Windows.Foundation;
-using Windows.Foundation.Collections;
-using Microsoft.UI.Xaml;
-using Microsoft.UI.Xaml.Controls;
-using Microsoft.UI.Xaml.Controls.Primitives;
-using Microsoft.UI.Xaml.Data;
-using Microsoft.UI.Xaml.Input;
-using Microsoft.UI.Xaml.Media;
-using Microsoft.UI.Xaml.Navigation;
-using Microsoft.UI.Xaml.Shapes;
+using Microsoft.UI.Xaml;
 using WinRT.Interop;
 
-// To learn more about WinUI, the WinUI project structure,
-// and more about our project templates, see: http://aka.ms/winui-project-info.
-
 namespace AmiReel;
 
 /// <summary>
@@ -24,7 +10,7 @@ public partial class App : Application
 {
     private Window? _window;
     public static IntPtr MainWindowHandle { get; private set; }
-    public static MainWindow? MainWindowInstance { get; set; }
+    public static MainWindow? MainWindowInstance { get; internal set; }
 
     /// <summary>
     /// Initializes the singleton application object.  This is the first line of authored code

MainPage.xaml

@@ -113,7 +113,8 @@
 
             <StackPanel Grid.Column="1" Orientation="Horizontal" Spacing="10">
                 <Button x:Name="OpenSettingsButton" Content="&#xE713;" FontFamily="Segoe Fluent Icons, Segoe MDL2 Assets"
-                        Click="OpenSettings_Click" Style="{StaticResource IconButtonStyle}" ToolTipService.ToolTip="Settings" />
+                        Click="OpenSettings_Click" Style="{StaticResource IconButtonStyle}"
+                        ToolTipService.ToolTip="Settings" AutomationProperties.Name="Settings" />
                 <Button x:Name="CancelButton" Content="Cancel" Click="Cancel_Click" IsEnabled="False" />
                 <Button x:Name="RenderButton" Content="Start render" Click="Render_Click" Style="{StaticResource PrimaryButtonStyle}" />
             </StackPanel>

MainPage.xaml.cs

@@ -6,7 +6,6 @@ using AmiReel.Models;
 using AmiReel.Services;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
-using Microsoft.Win32;
 using Windows.ApplicationModel.DataTransfer;
 using Windows.Storage;
 using Windows.Storage.Pickers;

Package.appxmanifest

@@ -5,8 +5,7 @@
   xmlns:mp="http://schemas.microsoft.com/appx/2014/phone/manifest"
   xmlns:uap="http://schemas.microsoft.com/appx/manifest/uap/windows10"
   xmlns:rescap="http://schemas.microsoft.com/appx/manifest/foundation/windows10/restrictedcapabilities"
-  xmlns:systemai="http://schemas.microsoft.com/appx/manifest/systemai/windows10"
-  IgnorableNamespaces="uap rescap systemai">
+  IgnorableNamespaces="uap rescap">
 
   <Identity
     Name="F004AE73-5989-46F3-B913-E9A3A355713F"
@@ -48,6 +47,5 @@
 
   <Capabilities>
     <rescap:Capability Name="runFullTrust" />
-    <systemai:Capability Name="systemAIModels"/>
   </Capabilities>
 </Package>