refactor: extract pay page components and migrate zpay → easypay

Components:
- Add PayPageLayout, OrderFilterBar, MobileOrderList, OrderTable, OrderSummaryCards
- Extract shared pay-utils (types, constants, helper functions)
- Simplify pay/page.tsx and orders/page.tsx

EasyPay migration:
- Remove src/lib/zpay/, api/zpay/notify, zpay test, zpay.md
- Simplify config.ts: single envSchema, no ZPAY_* fallback
- Rename DB field zpay_trade_no → payment_trade_no (migration added)
- Update OrderDetail label: ZPAY订单号 → 支付单号
- Update CLAUDE.md project structure

src/app/api/zpay/notify/route.ts

@@ -1,34 +0,0 @@
-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);
-
-    // ZPAY requires plain text response
-    return new Response(success ? 'success' : 'fail', {
-      headers: { 'Content-Type': 'text/plain' },
-    });
-  } catch (error) {
-    console.error('ZPAY notify error:', error);
-    return new Response('fail', {
-      headers: { 'Content-Type': 'text/plain' },
-    });
-  }
-}