feat: add isPast() and isFuture() time convenience methods

[datamweb]

Description

These methods reduce cognitive load by removing the need to mentally parse isBefore(Time::now()) or isAfter(Time::now()). The method name describes exactly what state we are checking for, rather than how we are calculating it.

See : https://forum.codeigniter.com/showthread.php?tid=92487

$coupon = $couponModel->find($code);

if ($coupon->expires_at->isPast()) {
    echo 'This discount code has expired.';
}

if ($article->publish_at->isFuture()) {
    return view('coming_soon');
}

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value (without duplication)
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[neznaika0]

Good.