BitNav items can't show a badge or a counter without replacing their default content #13688

Navigation menus often mark an item with a badge or a counter, such as "New" or "3". BitNavItem has no place for that kind of trailing content, and BitNavPanel uses the same items. Template with the Normal render mode replaces the item's icon and text, so adding a badge means rebuilding both and copying internal class names to keep the default look, which breaks whenever those names change.

Expected: a nav item can show a badge or a counter next to its text while keeping its default icon, text and states.