feat: 支付宝直连 H5 端使用 wap.pay 唤起支付宝 APP

前端传递 is_mobile 参数，AlipayProvider 根据设备类型选择：
- PC: alipay.trade.page.pay (FAST_INSTANT_TRADE_PAY)
- H5: alipay.trade.wap.pay (QUICK_WAP_WAY)

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

src/lib/alipay/provider.ts

@@ -22,16 +22,20 @@ export class AlipayProvider implements PaymentProvider {
   };
 
   async createPayment(request: CreatePaymentRequest): Promise<CreatePaymentResponse> {
+    const method = request.isMobile ? 'alipay.trade.wap.pay' : 'alipay.trade.page.pay';
+    const productCode = request.isMobile ? 'QUICK_WAP_WAY' : 'FAST_INSTANT_TRADE_PAY';
+
     const url = pageExecute(
       {
         out_trade_no: request.orderId,
-        product_code: 'FAST_INSTANT_TRADE_PAY',
+        product_code: productCode,
         total_amount: request.amount.toFixed(2),
         subject: request.subject,
       },
       {
         notifyUrl: request.notifyUrl,
         returnUrl: request.returnUrl,
+        method,
       },
     );