The main process already showed a system notification when an update finished
downloading, and nothing in the renderer listened — so the only cue vanished on
its own and was missed by anyone not watching the desktop at that moment.
A prompt now stays in the window until it is acted on or dismissed, with the
restart wired to the install-update channel the preload already exposed.
Dismissing is 'not now', not 'never': a later version reopens the prompt, since
the version it refers to has changed.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
