fix: replace mb_strlen/mb_substr with strlen/substr — mbstring not available on prod

src/SearchController.php

@@ -211,7 +211,7 @@ class SearchController
             $out = [];
             foreach ($raw as $v) {
                 $v = trim((string)$v);
-                if ($v !== '' && mb_strlen($v) <= $maxLen) {
+                if ($v !== '' && strlen($v) <= $maxLen) {
                     $out[] = $v;
                 }
             }