feat(helpdesk): align module with core list/drawer standards

- add helpdesk module pages, services, settings and tests

- standardize debtor list on drawer/grid contracts and robust filter drawer behavior

- add helpdesk aside panel navigation and settings visibility provider

- switch primary list slug to helpdesk/debitor and remove helpdesk/search compatibility

- include required core contract updates for list contracts and detail/drawer integration

config/modules.php

@@ -12,5 +12,5 @@
  * Each entry must match a directory name under modules/ containing a module.php manifest.
  */
 return [
-    'enabled_modules' => ['audit', 'addressbook', 'bookmarks', 'notifications', 'api-docs', 'help-center'],
+    'enabled_modules' => ['audit', 'addressbook', 'bookmarks', 'notifications', 'api-docs', 'help-center', 'helpdesk'],
 ];