Review point (#2950, comment 3444116036): when the surrounding task
<dialog> closed while the link prompt was open, the prompt was orphaned
and cleanup() never ran, leaking listeners and an unresolved promise.
Treat the prompt as a sub-modal of the task dialog: pressing Escape while
it is open now preventDefault()/stopPropagation()s the keydown so the
native modal <dialog> does not close on Escape, resolves the prompt with
'' (cancel) and runs cleanup() — only the prompt is dismissed, the task
dialog stays open. A one-shot 'cancel' listener on the enclosing dialog
backs this up in case the keydown handling is insufficient in some browser.
Tighten cleanup() so the prompt fully tears down regardless of how it
closes (Enter / Escape / click-outside): it now removes the scroll
listener, the document click listener and the dialog cancel listener, and
removes the element. handleClickOutside was hoisted so cleanup() can
remove it, closing the leaked-listener gap directly.
Adds an e2e asserting Escape cancels the prompt while the task dialog
stays open; the existing 'Enter creates the link' case still passes.
0e17556a16