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/admin/orders/[id]/route.ts

@@ -0,0 +1,31 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { prisma } from '@/lib/db';
+import { verifyAdminToken, unauthorizedResponse } from '@/lib/admin-auth';
+
+export async function GET(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  if (!verifyAdminToken(request)) return unauthorizedResponse();
+
+  const { id } = await params;
+
+  const order = await prisma.order.findUnique({
+    where: { id },
+    include: {
+      auditLogs: {
+        orderBy: { createdAt: 'desc' },
+      },
+    },
+  });
+
+  if (!order) {
+    return NextResponse.json({ error: '订单不存在' }, { status: 404 });
+  }
+
+  return NextResponse.json({
+    ...order,
+    amount: Number(order.amount),
+    refundAmount: order.refundAmount ? Number(order.refundAmount) : null,
+  });
+}