fix: turns out the namespace was called "Project" and has ID 4

https://www.mediawiki.org/wiki/Manual:$wgMetaNamespace

Author: harshkhandeparkar

mediawiki/LocalSettings.php

@@ -244,7 +244,7 @@
 
 $wgVisualEditorAvailableNamespaces = [
   "Help" => true,
-  $wgMetaNamespace => true,
+  4 => true,
   "Template" => true,
 ];