feat: add drag-and-drop tariff sorting in admin panel

Implement DnD reorder for tariffs using @dnd-kit, matching the
pattern from AdminPaymentMethods. Add updateOrder API method
and i18n keys for all locales.

src/locales/en.json

@@ -1306,6 +1306,9 @@
       "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",
+      "saveOrder": "Save order",
+      "orderSaved": "Order saved",
+      "dragToReorder": "Drag to reorder",
       "days": "days",
       "days_one": "{{count}} day",
       "days_other": "{{count}} days",