Civi extension: register xml/Menu via hook_civicrm_xmlMenu

The Engagement Report tab on Organization contact pages was loading the
contact-view summary recursively inside its own tab pane. Root cause:
Civi's menu router was not picking up the extension's xml/Menu file, so
`civicrm/contact/view/engagement-report` fell back to the parent
`civicrm/contact/view` route. Adding an explicit hook_civicrm_xmlMenu
implementation forces the menu file to register, after which the route
resolves to CRM_WebformMw_Page_Tab and the iframe renders as intended.

Deploy: replace the extension files on the Civi server, then in
Administer → System Settings → Extensions Disable + re-Enable webform-mw
(or run `cv flush` on the server) so the menu cache is rebuilt.

civi-extension/webform-mw/webform_mw.php

@@ -37,6 +37,20 @@ function _webform_mw_staff_key(): string {
   return is_string($env) ? $env : '';
 }
 
+/**
+ * Implements hook_civicrm_xmlMenu().
+ *
+ * Registers this extension's menu file. Civi 5.50+ usually auto-discovers
+ * `xml/Menu/*.xml` from extensions, but some installations only pick the
+ * file up when an explicit hook returns it. Without this the new path
+ * `civicrm/contact/view/engagement-report` falls back to the parent
+ * `civicrm/contact/view` route and the tab pane recursively embeds the
+ * contact-view summary instead of our iframe.
+ */
+function webform_mw_civicrm_xmlMenu(&$files) {
+  $files[] = __DIR__ . '/xml/Menu/webform_mw.xml';
+}
+
 /**
  * Implements hook_civicrm_tabset().
  *