refactor: 常量化订单状态 + 支付渠道/提供商分离显示 + H5自动跳转

- 新增 src/lib/constants.ts，集中管理 ORDER_STATUS / PAYMENT_TYPE / PAYMENT_PREFIX 等常量
- 后端 service/status/timeout/limits 全量替换魔法字符串为 ORDER_STATUS.*
- PaymentTypeMeta 新增 provider 字段，分离 sublabel（选择器展示）与 provider（提供商名称）
- getPaymentDisplayInfo() 返回 { channel, provider } 用于用户端/管理端展示
- 支持通过 PAYMENT_SUBLABEL_* 环境变量覆盖默认 sublabel
- PaymentQRCode: H5 支付自动跳转（含易支付微信 weixin:// scheme 兜底）
- 订单列表/详情页：显示可读的渠道名+提供商，不再暴露内部标识符

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

src/components/OrderTable.tsx

@@ -1,4 +1,4 @@
-import { formatStatus, formatCreatedAt, getStatusBadgeClass, type MyOrder } from '@/lib/pay-utils';
+import { formatStatus, formatCreatedAt, getStatusBadgeClass, getPaymentDisplayInfo, type MyOrder } from '@/lib/pay-utils';
 
 interface OrderTableProps {
   isDark: boolean;
@@ -67,7 +67,21 @@ export default function OrderTable({ isDark, loading, error, orders }: OrderTabl
               >
                 <div className="font-medium">#{order.id.slice(0, 12)}</div>
                 <div className="font-semibold">¥{order.amount.toFixed(2)}</div>
-                <div>{order.paymentType}</div>
+                <div>
+                  {(() => {
+                    const { channel, provider } = getPaymentDisplayInfo(order.paymentType);
+                    return (
+                      <>
+                        <span>{channel}</span>
+                        {provider && (
+                          <span className={['ml-1 text-xs', isDark ? 'text-slate-400' : 'text-slate-500'].join(' ')}>
+                            {provider}
+                          </span>
+                        )}
+                      </>
+                    );
+                  })()}
+                </div>
                 <div>
                   <span
                     className={['rounded-full px-2 py-0.5 text-xs', getStatusBadgeClass(order.status, isDark)].join(