fix(ns): root-qualify PHP builtins after PSR-4 move

Namespaced classes resolved DateTimeImmutable etc. under AKSRT\*
(e.g. Credits\DateTimeImmutable). Prefix with \ globally.

src/AKSRT/Credits/Earn.php

@@ -57,7 +57,7 @@ class Earn {
 		if ($user_id <= 0 || !class_exists('PointsFree')) {
 			return;
 		}
-		$today = (new DateTimeImmutable('today', wp_timezone()))->format('Y-m-d');
+		$today = (new \DateTimeImmutable('today', wp_timezone()))->format('Y-m-d');
 		$last  = (string) get_user_meta($user_id, PointsFree::META_LOGIN, true);
 		if ($last === $today) {
 			return;