The update-not-available event only logged silently; the promise-based
fallback incorrectly checked result.updateInfo (which exists even when
no update is available). Replaced with a one-time event listener scoped
to the manual check so "You are running the latest version" dialog
appears correctly. Also bumps to 1.0.2.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>