Store Admin navigation now stays open when viewing expandable menu items

We've improved the Store Admin navigation behavior on mobile. Previously, tapping an expandable menu item would open the page and close the side menu at the same time, making it tedious to jump between related sub-items. Now the expandable item appears as the first entry in its sub-menu, so you can open the page while keeping the menu open. This matches the behavior you're already familiar with in hPanel, making navigation smoother and more intuitive.