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/zh.json

@@ -1050,6 +1050,9 @@
       "confirmDeleteText": "此操作不可撤销。套餐将被永久删除。",
       "confirmDeleteWithSubscriptions": "此套餐有 {{count}} 个活跃订阅。删除后，用户续订时需要选择新套餐。",
       "deleteSuccess": "套餐删除成功",
+      "saveOrder": "保存排序",
+      "orderSaved": "排序已保存",
+      "dragToReorder": "拖动以重新排序",
       "days": "天",
       "days_other": "{{count}} 天",
       "tabs": {