fix: improve Toast visibility and allow tariff deletion with subscriptions

- Toast: use solid bg-dark-800 background instead of transparent gradient
- Toast: increase border opacity for better visibility
- Tariffs: allow deletion even with active subscriptions (shows warning)
- Add confirmDeleteWithSubscriptions translation to all locales

src/locales/en.json

@@ -1215,9 +1215,9 @@
       "deactivate": "Deactivate",
       "toggleTrial": "Toggle Trial",
       "delete": "Delete",
-      "cannotDeleteHasSubscriptions": "Cannot delete: has active subscriptions",
       "confirmDelete": "Delete tariff?",
       "confirmDeleteText": "This action cannot be undone. The tariff will be permanently deleted.",
+      "confirmDeleteWithSubscriptions": "This tariff has {{count}} active subscriptions. After deletion, users will need to select a new tariff when renewing.",
       "deleteSuccess": "Tariff deleted successfully",
       "days": "days",
       "days_one": "{{count}} day",