fix(web): background announcements don't repeat in-app notification toasts

The toast viewport is a polite live region, so with in-app notifications on a
background thread finishing was read twice.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2cf37ee452PR Batch Tester committed on 10/23/2026, 12:19:00 PMparent0a6517d
1 file changedLine totals unavailable