Moved the open handler from the child <atom:menu> (x-on:popover-open, arrow-wrapped,
never fired) to <atom:dropdown x-on:open="..."> where dropdown.js fires the event,
and wired the previously-dead link-menu-on listener so the link-active case shows
the current link. +2 e2e guards (create + edit).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>