dayLabel function
"Today", "Yesterday" or the date, for a day separator.
Implementation
String dayLabel(DateTime at, HatangLocale locale, HatangChatStrings strings, {DateTime? now}) {
final day = dayOf(at);
final today = dayOf(now ?? clock.now());
if (day == today) return strings.today;
if (day == today.subtract(const Duration(days: 1))) return strings.yesterday;
return dateOf(at, locale);
}