Add UpdateTitleViewInternal for iOS 26+ compatibility

Introduces UpdateTitleViewInternal in ShellPageRendererTracker and calls it from ShellSectionRenderer for iOS 26+ and Mac Catalyst 26+. This ensures TitleView is updated correctly when the ViewController is added to a NavigationController, addressing layout issues on newer OS versions.

Author: kubaflo

src/Controls/src/Core/Compatibility/Handlers/Shell/iOS/ShellPageRendererTracker.cs

@@ -271,6 +271,11 @@ protected virtual void OnRendererSet()
 				ViewController.AutomaticallyAdjustsScrollViewInsets = false;
 			}
 		}
+		
+		internal void UpdateTitleViewInternal()
+		{
+			UpdateTitleView();
+		}
 
 		protected virtual void UpdateTitleView()
 		{

src/Controls/src/Core/Compatibility/Handlers/Shell/iOS/ShellSectionRenderer.cs

@@ -824,6 +824,13 @@ public override void WillShowViewController(UINavigationController navigationCon
 					tracker is ShellPageRendererTracker shellRendererTracker)
 				{
 					shellRendererTracker.UpdateToolbarItemsInternal(false);
+					if (OperatingSystem.IsIOSVersionAtLeast(26) || OperatingSystem.IsMacCatalystVersionAtLeast(26))
+					{
+						// If we are on iOS 26+ and the ViewController is not in a NavigationController yet,
+						// we cannot set the TitleView yet as it would not layout correctly.
+						// So we update it later when the ViewController is added to the NavigationController
+						shellRendererTracker.UpdateTitleViewInternal();
+					}
 				}
 			}