The cleanup for the announcement-toast effect only cleared the outer
1500ms timer, leaving the per-announcement stagger timers (i * 800ms)
untracked. If the root layout unmounts during the stagger window, those
timers fire after cleanup and attempt to toast against a dead tree.
Track the inner timer ids in an array and clear them alongside the outer
timer in the effect cleanup.
Fixes#1094.
- Added startTime and endTime properties to announcements for time-bound visibility.
- Introduced audience targeting to control who sees announcements (all, users, web_visitors).
- Updated related components and hooks to support new announcement features.
- Removed unused state tracking for dismissed announcements to streamline functionality.
