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

@@ -0,0 +1,37 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { z } from 'zod';
+import { cancelOrder, OrderError } from '@/lib/order/service';
+
+const cancelSchema = z.object({
+  user_id: z.number().int().positive(),
+});
+
+export async function POST(
+  request: NextRequest,
+  { params }: { params: Promise<{ id: string }> },
+) {
+  try {
+    const { id } = await params;
+    const body = await request.json();
+    const parsed = cancelSchema.safeParse(body);
+
+    if (!parsed.success) {
+      return NextResponse.json(
+        { error: '参数错误', details: parsed.error.flatten().fieldErrors },
+        { status: 400 },
+      );
+    }
+
+    await cancelOrder(id, parsed.data.user_id);
+    return NextResponse.json({ success: true });
+  } catch (error) {
+    if (error instanceof OrderError) {
+      return NextResponse.json(
+        { error: error.message, code: error.code },
+        { status: error.statusCode },
+      );
+    }
+    console.error('Cancel order error:', error);
+    return NextResponse.json({ error: '取消订单失败' }, { status: 500 });
+  }
+}