Menu-button pattern built on the native Popover API. The menu is a popover the trigger toggles through popovertarget, so opening, closing, Escape, and light-dismiss all work with no JavaScript, and CSS anchor positioning places it. This enhancer adds the menu semantics the platform doesn't: role="menu" wiring, roving focus into the items on open, arrow/Home/End/typeahead navigation, and a JS positioning fallback for engines without anchor positioning. Open state is observable through onOpenChange/hl:open-change and activating an item emits a cancelable hl:select.