Fix caching issue on admin page

admin/main.php

@@ -203,6 +203,12 @@ class admin_plugin_luxtools_main extends DokuWiki_Admin_Plugin
             $ok = @file_put_contents($file, $content, LOCK_EX) !== false;
         }
 
+        // Ensure the updated conf/local.php is picked up immediately even when
+        // OPcache is configured to revalidate infrequently (e.g. revalidate_freq=60).
+        if ($ok && function_exists('opcache_invalidate')) {
+            @opcache_invalidate($file, true);
+        }
+
         // Best-effort cleanup: stop creating/using legacy conf/plugins/luxtools.local.php
         $legacy = DOKU_CONF . 'plugins/' . $plugin . '.local.php';
         if (@is_file($legacy)) {