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>

i18n/default_de.json

@@ -2,6 +2,9 @@
   "Login": "Login",
   "Login credentials": "Mit Zugangsdaten oder SSO anmelden",
   "Login provider": "Login-Anbieter",
+  "Open full page": "Vollseite öffnen",
+  "Loading": "Lädt",
+  "Failed to load": "Laden fehlgeschlagen",
   "Register": "Registrieren",
   "Password": "Passwort",
   "Or": "Oder",

i18n/default_en.json

@@ -2,6 +2,9 @@
   "Login": "Login",
   "Login credentials": "Login credentials",
   "Login provider": "Login provider",
+  "Open full page": "Open full page",
+  "Loading": "Loading",
+  "Failed to load": "Failed to load",
   "Register": "Register",
   "Password": "Password",
   "Or": "Or",