Items on the lists page and dashboard widget now show as crossed-out for
a configurable duration (default 3s) before vanishing. Unchecking within
the window cancels the removal. The delay is stored in localStorage and
configurable via Settings → Lists (options: 1s / 3s / 5s / 10s / 30s).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>