Add time comparison methods to ChronosTime

[dereuromark]

Summary

Adds four new methods to ChronosTime for checking if a time instance represents common boundary times:

• isStartOfDay(): Checks if time is 00:00:00.000000
• isEndOfDay(): Checks if time is 23:59:59 (ignores microseconds)
• isMidnight(): Alias for isStartOfDay()
• isMidday(): Checks if time is 12:00:00.000000

Example Usage

$time = ChronosTime::midnight();
$time->isStartOfDay(); // true
$time->isMidnight();   // true

$time = ChronosTime::noon();
$time->isMidday(); // true

$time = ChronosTime::endOfDay();
$time->isEndOfDay(); // true