Fix title bar icon missing in single-file published builds

The title bar Image used Source="ms-appx:///Assets/Square44x44Logo.scale-200.png".
That resolves fine in a normal build (Assets/ and AmiReel.pri sit next to the exe),
but a single-file self-contained publish (IncludeAllContentForSelfExtract=true)
bundles Content items into the exe in a way ms-appx:// can no longer resolve at
runtime, leaving the title bar icon blank — reproduced with the actual
publish-win-x64.ps1 output, confirmed fixed the same way.

Load the icon from a plain embedded resource instead (same mechanism already
used for ffmpeg.exe/ffprobe.exe): the PNG is embedded via
<EmbeddedResource LogicalName="AmiReel.Assets.TitleBarIcon.png">, and
MainWindow loads it at startup via GetManifestResourceStream + BitmapImage.
SetSourceAsync. This bypasses the ms-appx/MRT resource pipeline entirely, so
it behaves identically in dotnet build, dotnet run, and a single-file publish.

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

AmiReel.csproj

@@ -46,6 +46,11 @@
   <ItemGroup>
     <EmbeddedResource Include="ThirdParty\ffmpeg.exe" Condition="Exists('ThirdParty\ffmpeg.exe')" LogicalName="AmiReel.Tools.ffmpeg.exe" />
     <EmbeddedResource Include="ThirdParty\ffprobe.exe" Condition="Exists('ThirdParty\ffprobe.exe')" LogicalName="AmiReel.Tools.ffprobe.exe" />
+    <!-- Loaded at runtime via GetManifestResourceStream for the title bar icon (MainWindow.xaml.cs).
+         The Assets\*.png Content items above go through the ms-appx:// / MRT resource pipeline,
+         which a single-file self-contained publish bundles into the exe in a way that ms-appx://
+         can no longer resolve at runtime — this embedded copy sidesteps that entirely. -->
+    <EmbeddedResource Include="Assets\Square44x44Logo.scale-200.png" LogicalName="AmiReel.Assets.TitleBarIcon.png" />
   </ItemGroup>
 
   <!--

MainWindow.xaml

@@ -16,7 +16,7 @@
 
         <Grid x:Name="AppTitleBar" Grid.Row="0" Height="44" Background="{ThemeResource PanelBrush}">
             <StackPanel Orientation="Horizontal" Spacing="10" VerticalAlignment="Center" Margin="14,0,0,0">
-                <Image Source="ms-appx:///Assets/Square44x44Logo.scale-200.png"
+                <Image x:Name="TitleBarIcon"
                        Width="20"
                        Height="20"
                        Stretch="Uniform" />

MainWindow.xaml.cs

@@ -2,9 +2,12 @@ using Microsoft.UI;
 using Microsoft.UI.Windowing;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Media.Imaging;
 using System;
 using System.IO;
+using System.Reflection;
 using System.Runtime.InteropServices;
+using System.Runtime.InteropServices.WindowsRuntime;
 using Windows.Graphics;
 using Windows.UI;
 using WinRT.Interop;
@@ -36,6 +39,7 @@ public sealed partial class MainWindow : Window
             AppWindow.SetIcon(executablePath);
 
         SetDefaultSizeAndPosition();
+        LoadTitleBarIcon();
 
         // Navigate the root frame to the main page on startup.
         RootFrame.Navigate(typeof(MainPage));
@@ -43,6 +47,30 @@ public sealed partial class MainWindow : Window
         AppWindow.Closing += AppWindow_Closing;
     }
 
+    /// <summary>
+    /// Loads the title bar icon from an embedded resource instead of an "ms-appx:///Assets/..."
+    /// URI. A single-file self-contained publish bundles Content/Assets items into the exe in a
+    /// way the ms-appx resource pipeline can no longer resolve at runtime, leaving the title bar
+    /// blank; a plain embedded resource stream works the same in every publish mode.
+    /// </summary>
+    private async void LoadTitleBarIcon()
+    {
+        try
+        {
+            Assembly assembly = Assembly.GetExecutingAssembly();
+            using Stream? stream = assembly.GetManifestResourceStream("AmiReel.Assets.TitleBarIcon.png");
+            if (stream is null) return;
+
+            BitmapImage bitmap = new();
+            await bitmap.SetSourceAsync(stream.AsRandomAccessStream());
+            TitleBarIcon.Source = bitmap;
+        }
+        catch
+        {
+            // Non-critical: the title bar simply shows no icon if this fails.
+        }
+    }
+
     private void SetDefaultSizeAndPosition()
     {
         const int DefaultWidth = 1280;