Wiring a component shell provides so CngxMenuItemSubmenu resolves its
popover and inner menu from DI instead of from [cngxMenuItemSubmenu] /
[submenuMenu] inputs. Lets @cngx/ui/context-menu wire the submenu
brain internally (Bridge-Input-Regel) - the brain stays inert (no
aria-haspopup / aria-expanded) until one source is present.