Use KST for car monitor timestamps

common.php

@@ -1,6 +1,8 @@
-<?php
+<?php
 declare(strict_types=1);
 
+date_default_timezone_set('Asia/Seoul');
+
 $carSecretFile = '/home/seo/secret/car.php';
 if (!is_file($carSecretFile)) {
     throw new RuntimeException('Missing car secret config: ' . $carSecretFile);