chore(drawer): close consolidation gaps after three-consumer rollout

Loose ends surfaced by comparing the three drawer consumers side by side:

- Core i18n was missing `Open full page`, `Loading`, `Failed to load` —
  admin/users showed English strings in the German UI because those labels
  resolve from core, not module catalogs.
- Helpdesk tickets page config did not pass drawer labels; the JS fell back
  to its hard-coded English defaults. Labels now wired via `t(...)`.
- CLAUDE.md notes the `fetchUrl` single-expression convention (required so
  the architecture test can statically locate the fragment path) and
  documents the `onContentLoaded` hook for module-specific runtime
  (helpdesk's async communication feed uses it).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

modules/helpdesk/pages/helpdesk/debitor(default).phtml

@@ -351,6 +351,12 @@ $searchConfig = is_array($searchConfig ?? null) ? $searchConfig : null;
         'support' => t('Support'),
         'created' => t('Created'),
         'lastActivity' => t('Last activity'),
+        'drawerClose' => t('Close'),
+        'drawerPrev' => t('Previous'),
+        'drawerNext' => t('Next'),
+        'drawerOpenFull' => t('Open full page'),
+        'drawerLoading' => t('Loading'),
+        'drawerError' => t('Failed to load'),
     ],
     'gridSearch' => $searchConfig,
     'filterSchema' => $clientFilterSchema,