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/refund/route.ts

@@ -0,0 +1,43 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { z } from 'zod';
+import { verifyAdminToken, unauthorizedResponse } from '@/lib/admin-auth';
+import { processRefund, OrderError } from '@/lib/order/service';
+
+const refundSchema = z.object({
+  order_id: z.string().min(1),
+  reason: z.string().optional(),
+  force: z.boolean().optional().default(false),
+});
+
+export async function POST(request: NextRequest) {
+  if (!verifyAdminToken(request)) return unauthorizedResponse();
+
+  try {
+    const body = await request.json();
+    const parsed = refundSchema.safeParse(body);
+
+    if (!parsed.success) {
+      return NextResponse.json(
+        { error: '参数错误', details: parsed.error.flatten().fieldErrors },
+        { status: 400 },
+      );
+    }
+
+    const result = await processRefund({
+      orderId: parsed.data.order_id,
+      reason: parsed.data.reason,
+      force: parsed.data.force,
+    });
+
+    return NextResponse.json(result);
+  } catch (error) {
+    if (error instanceof OrderError) {
+      return NextResponse.json(
+        { error: error.message, code: error.code },
+        { status: error.statusCode },
+      );
+    }
+    console.error('Refund error:', error);
+    return NextResponse.json({ error: '退款失败' }, { status: 500 });
+  }
+}