fix: add missing global declaration for menu icon override in Options

getOptionsHTML() was missing the global $menuIconOverride declaration,
so custom image icons set for the Options menu item were ignored in
the left sidebar, always falling back to the default material icon.

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

web/skins/classic/includes/functions.php

@@ -1123,6 +1123,7 @@ function getOptionsHTML($forLeftBar = false, $customLabel = null) {
       </div>
       ';
 
+      global $menuIconOverride;
       $optIcon = 'settings';
       $optIconType = 'material';
       if (isset($menuIconOverride)) {