temp: check GD availability

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

gdcheck.php

@@ -0,0 +1,6 @@
+<?php
+echo "GD: " . (extension_loaded('gd') ? 'KYLLÄ' : 'EI') . "\n";
+echo "Imagick: " . (extension_loaded('imagick') ? 'KYLLÄ' : 'EI') . "\n";
+if (extension_loaded('gd')) {
+    echo "GD info: " . json_encode(gd_info()) . "\n";
+}