Show the full version in the title bar on DEBUG builds

Matches the WPF behaviour at master:ILSpy/AssemblyTree/AssemblyTreeModel.cs:440
where DEBUG builds get "ILSpy {DecompilerVersionInfo.FullVersion}" so the
developer can tell from a glance which build the running window came from
(especially handy when the avalonia-preview tag floats forward and several
windows are open at once). Release builds keep the bare "ILSpy" title.

The title is bound from MainWindowViewModel.Title (axaml: Title="{Binding
Title}"), so threading the version through the VM is the natural seam --
no axaml change and the bound value can later be made notifying if we
want to mix in the active assembly-list name.

Assisted-by: Claude:claude-opus-4-7:Claude Code

ILSpy.Tests/MainWindow/MainWindowTests.cs

@@ -53,7 +53,9 @@ public class MainWindowTests
 
 		// Assert — visible, titled, with the correct DataContext.
 		window.IsVisible.Should().BeTrue();
-		window.Title.Should().Be("ILSpy");
+		// DEBUG builds append the full version (e.g. "ILSpy 11.0.0.x-<branch>-pre") to the
+		// title bar, so match the prefix rather than the exact string.
+		window.Title.Should().StartWith("ILSpy");
 		window.DataContext.Should().BeOfType<MainWindowViewModel>();
 	}
 

ILSpy/ViewModels/MainWindowViewModel.cs

@@ -44,7 +44,12 @@ namespace ILSpy.ViewModels
 
 		public System.Collections.Generic.IReadOnlyList<ToolPaneMenuItem> ToolPaneMenuItems => DockWorkspace.ToolPaneMenuItems;
 
-		public string Title => "ILSpy";
+		public string Title =>
+#if DEBUG
+			$"ILSpy {DecompilerVersionInfo.FullVersion}";
+#else
+			"ILSpy";
+#endif
 
 		[ImportingConstructor]
 		public MainWindowViewModel(