feat: 全站多语言支持 (i18n)，lang=en 显示英文，其余默认中文

新增 src/lib/locale.ts 作为统一多语言入口，覆盖前台支付链路、
管理后台、API/服务层错误文案，共 35 个文件。URL 参数 lang 全链路透传，
包括 Stripe return_url、页面跳转、layout html lang 属性等。

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

src/components/OrderStatus.tsx

@@ -1,56 +1,99 @@
 'use client';
 
+import type { Locale } from '@/lib/locale';
+
 interface OrderStatusProps {
   status: string;
   onBack: () => void;
   dark?: boolean;
+  locale?: Locale;
 }
 
-const STATUS_CONFIG: Record<string, { label: string; color: string; icon: string; message: string }> = {
-  COMPLETED: {
-    label: '充值成功',
-    color: 'text-green-600',
-    icon: '✓',
-    message: '余额已到账，感谢您的充值！',
+const STATUS_CONFIG: Record<Locale, Record<string, { label: string; color: string; icon: string; message: string }>> = {
+  zh: {
+    COMPLETED: {
+      label: '充值成功',
+      color: 'text-green-600',
+      icon: '✓',
+      message: '余额已到账，感谢您的充值！',
+    },
+    PAID: {
+      label: '充值中',
+      color: 'text-blue-600',
+      icon: '⟳',
+      message: '支付成功，正在充值余额中...',
+    },
+    RECHARGING: {
+      label: '充值中',
+      color: 'text-blue-600',
+      icon: '⟳',
+      message: '正在充值余额中，请稍候...',
+    },
+    FAILED: {
+      label: '充值失败',
+      color: 'text-red-600',
+      icon: '✗',
+      message: '充值失败，请联系管理员处理。',
+    },
+    EXPIRED: {
+      label: '订单超时',
+      color: 'text-gray-500',
+      icon: '⏰',
+      message: '订单已超时，请重新创建订单。',
+    },
+    CANCELLED: {
+      label: '已取消',
+      color: 'text-gray-500',
+      icon: '✗',
+      message: '订单已取消。',
+    },
   },
-  PAID: {
-    label: '充值中',
-    color: 'text-blue-600',
-    icon: '⟳',
-    message: '支付成功，正在充值余额中...',
-  },
-  RECHARGING: {
-    label: '充值中',
-    color: 'text-blue-600',
-    icon: '⟳',
-    message: '正在充值余额中，请稍候...',
-  },
-  FAILED: {
-    label: '充值失败',
-    color: 'text-red-600',
-    icon: '✗',
-    message: '充值失败，请联系管理员处理。',
-  },
-  EXPIRED: {
-    label: '订单超时',
-    color: 'text-gray-500',
-    icon: '⏰',
-    message: '订单已超时，请重新创建订单。',
-  },
-  CANCELLED: {
-    label: '已取消',
-    color: 'text-gray-500',
-    icon: '✗',
-    message: '订单已取消。',
+  en: {
+    COMPLETED: {
+      label: 'Recharge Successful',
+      color: 'text-green-600',
+      icon: '✓',
+      message: 'Your balance has been credited. Thank you for your payment.',
+    },
+    PAID: {
+      label: 'Recharging',
+      color: 'text-blue-600',
+      icon: '⟳',
+      message: 'Payment received. Recharging your balance...',
+    },
+    RECHARGING: {
+      label: 'Recharging',
+      color: 'text-blue-600',
+      icon: '⟳',
+      message: 'Recharging your balance. Please wait...',
+    },
+    FAILED: {
+      label: 'Recharge Failed',
+      color: 'text-red-600',
+      icon: '✗',
+      message: 'Recharge failed. Please contact the administrator.',
+    },
+    EXPIRED: {
+      label: 'Order Expired',
+      color: 'text-gray-500',
+      icon: '⏰',
+      message: 'This order has expired. Please create a new order.',
+    },
+    CANCELLED: {
+      label: 'Cancelled',
+      color: 'text-gray-500',
+      icon: '✗',
+      message: 'The order has been cancelled.',
+    },
   },
 };
 
-export default function OrderStatus({ status, onBack, dark = false }: OrderStatusProps) {
-  const config = STATUS_CONFIG[status] || {
+export default function OrderStatus({ status, onBack, dark = false, locale = 'zh' }: OrderStatusProps) {
+  const config = STATUS_CONFIG[locale][status] || {
     label: status,
     color: 'text-gray-600',
     icon: '?',
-    message: '未知状态',
+    message: locale === 'en' ? 'Unknown status' : '未知状态',
   };
 
   return (
@@ -65,7 +108,7 @@ export default function OrderStatus({ status, onBack, dark = false }: OrderStatu
           dark ? 'bg-blue-600 hover:bg-blue-500' : 'bg-blue-600 hover:bg-blue-700',
         ].join(' ')}
       >
-        {status === 'COMPLETED' ? '完成' : '返回充值'}
+        {status === 'COMPLETED' ? (locale === 'en' ? 'Done' : '完成') : locale === 'en' ? 'Back to Recharge' : '返回充值'}
       </button>
     </div>
   );