feat: migrate payment provider to easy-pay, add order history and refund support

- Replace zpay with easy-pay payment provider (new lib/easy-pay/ module)
- Add order history page for users (pay/orders)
- Add GET /api/orders/my endpoint to list user's own orders
- Add GET /api/users/[id] endpoint for sub2api user lookup
- Add order status tracking module (lib/order/status.ts)
- Update config to support easy-pay credentials (merchant ID, key, gateway)
- Update PaymentForm and PaymentQRCode components for easy-pay flow
- Update pay page and admin page with new order management UI
- Update order service to support easy-pay, cancellation, and refund

src/app/api/easy-pay/notify/route.ts

@@ -0,0 +1,32 @@
+import { NextRequest } from 'next/server';
+import { handlePaymentNotify } from '@/lib/order/service';
+import type { EasyPayNotifyParams } from '@/lib/easy-pay/types';
+
+export async function GET(request: NextRequest) {
+  try {
+    const searchParams = request.nextUrl.searchParams;
+
+    const params: EasyPayNotifyParams = {
+      pid: searchParams.get('pid') || '',
+      name: searchParams.get('name') || '',
+      money: searchParams.get('money') || '',
+      out_trade_no: searchParams.get('out_trade_no') || '',
+      trade_no: searchParams.get('trade_no') || '',
+      param: searchParams.get('param') || '',
+      trade_status: searchParams.get('trade_status') || '',
+      type: searchParams.get('type') || '',
+      sign: searchParams.get('sign') || '',
+      sign_type: searchParams.get('sign_type') || '',
+    };
+
+    const success = await handlePaymentNotify(params);
+    return new Response(success ? 'success' : 'fail', {
+      headers: { 'Content-Type': 'text/plain' },
+    });
+  } catch (error) {
+    console.error('EasyPay notify error:', error);
+    return new Response('fail', {
+      headers: { 'Content-Type': 'text/plain' },
+    });
+  }
+}