Fix status bar not updating on timer chain transition when app is unf…

…ocused

Native Swift timer now calls back to Dart on completion so the next
chained timer state is pushed to the status bar immediately, bypassing
the throttled Flutter widget rebuild path.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Bump version to 4.1.0 and add CHANGELOG

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

bump version to 4.0.2

initial commit