fix: EasyPay支付回调缺少access_token导致结果页显示"凭证缺失"

EasyPay provider未将动态returnUrl传递给底层client，
导致return_url使用静态环境变量，不含order_id和access_token参数。

src/lib/easy-pay/client.ts

@@ -8,6 +8,7 @@ export interface CreatePaymentOptions {
   paymentType: string;
   clientIp: string;
   productName: string;
+  returnUrl?: string;
 }
 
 function normalizeCidList(cid?: string): string | undefined {
@@ -56,7 +57,7 @@ export async function createPayment(opts: CreatePaymentOptions): Promise<EasyPay
     type: opts.paymentType,
     out_trade_no: opts.outTradeNo,
     notify_url: env.EASY_PAY_NOTIFY_URL,
-    return_url: env.EASY_PAY_RETURN_URL,
+    return_url: opts.returnUrl || env.EASY_PAY_RETURN_URL,
     name: opts.productName,
     money: opts.amount,
     clientip: opts.clientIp,

src/lib/easy-pay/provider.ts

@@ -28,6 +28,7 @@ export class EasyPayProvider implements PaymentProvider {
       paymentType: request.paymentType as 'alipay' | 'wxpay',
       clientIp: request.clientIp || '127.0.0.1',
       productName: request.subject,
+      returnUrl: request.returnUrl,
     });
 
     return {