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/zh.json

@@ -1027,9 +1027,9 @@
       "deactivate": "停用",
       "toggleTrial": "切换试用",
       "delete": "删除",
-      "cannotDeleteHasSubscriptions": "无法删除：有活跃订阅",
       "confirmDelete": "删除套餐？",
       "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",
       "days": "天",
       "days_other": "{{count}} 天",