fix(i18n): complete translations for production launch and fix CMS store context

- Replace CMS custom get_store_context() with core utility (same fix as loyalty)
- Add 85 missing translation keys across fr/de/lb for core, tenancy, messaging,
  customers, and loyalty modules
- Convert 21 client-side $t() calls to server-side _() in 9 loyalty templates
- Fix 3 broken translation keys in store/cards.html

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/modules/loyalty/locales/lb.json

@@ -78,6 +78,7 @@
         "terminal": "Terminal",
         "customer_cards": "Clientekaarten",
         "statistics": "Statistiken",
+        "program": "Programm",
         "overview": "Iwwersiicht",
         "settings": "Astellungen"
     },