Cover the bare MenuItem template branch

Adds the remaining flyout item shape an external backend can be handed: the
bare MenuItem whose template is set on its (internal) MenuShellItem wrapper,
reachable publicly as MenuItem.Parent, plus the no-template fallback for the
same shape.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: Redth

src/Controls/tests/Core.UnitTests/ShellExternalFlyoutBackendTests.cs

@@ -193,6 +193,42 @@ public void MenuItemTemplateSetOnParentIsFoundThroughMenuItem()
 			Assert.Equal("OnParent", ((Label)backend.CreateFlyoutItemView(menuItem)).Text);
 		}
 
+		[Fact]
+		public void BareMenuItemResolvesTemplateSetOnItsWrapper()
+		{
+			var shell = new Shell();
+			shell.Items.Add(CreateShellItem());
+
+			var menuItem = new MenuItem { Text = "Menu" };
+			AddMenuShellItem(shell, menuItem);
+
+			// The wrapper is internal, but it is reachable as the MenuItem's parent, and a template set there
+			// has to be found when the backend is handed the bare MenuItem.
+			var template = new DataTemplate(() => new Label { Text = "OnWrapper" });
+			Shell.SetMenuItemTemplate(menuItem.Parent, template);
+
+			var backend = new FakeExternalShellFlyoutBackend(shell);
+
+			Assert.False(menuItem.IsSet(Shell.MenuItemTemplateProperty));
+			Assert.Same(template, Shell.ResolveFlyoutItemTemplate(shell, menuItem));
+			Assert.Equal("OnWrapper", ((Label)backend.CreateFlyoutItemView(menuItem)).Text);
+		}
+
+		[Fact]
+		public void BareMenuItemWithoutTemplateResolvesToNull()
+		{
+			var shell = new Shell();
+			shell.Items.Add(CreateShellItem());
+
+			var menuItem = new MenuItem { Text = "Menu" };
+			AddMenuShellItem(shell, menuItem);
+
+			var backend = new FakeExternalShellFlyoutBackend(shell);
+
+			Assert.Null(Shell.ResolveFlyoutItemTemplate(shell, menuItem));
+			Assert.Equal(FakeExternalShellFlyoutBackend.PlatformDefaultText, ((Label)backend.CreateFlyoutItemView(menuItem)).Text);
+		}
+
 		[Fact]
 		public void MenuItemTemplateBindsTextAndCommandForShellContentMenuItems()
 		{