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/lib/pay-utils.ts

@@ -0,0 +1,70 @@
+export interface UserInfo {
+  id?: number;
+  username: string;
+  balance: number;
+}
+
+export interface MyOrder {
+  id: string;
+  amount: number;
+  status: string;
+  paymentType: string;
+  createdAt: string;
+}
+
+export type OrderStatusFilter = 'ALL' | 'PENDING' | 'PAID' | 'COMPLETED' | 'CANCELLED' | 'EXPIRED' | 'FAILED';
+
+export const STATUS_TEXT_MAP: Record<string, string> = {
+  PENDING: '待支付',
+  PAID: '已支付',
+  RECHARGING: '充值中',
+  COMPLETED: '已完成',
+  EXPIRED: '已超时',
+  CANCELLED: '已取消',
+  FAILED: '失败',
+  REFUNDING: '退款中',
+  REFUNDED: '已退款',
+  REFUND_FAILED: '退款失败',
+};
+
+export const FILTER_OPTIONS: { key: OrderStatusFilter; label: string }[] = [
+  { key: 'ALL', label: '全部' },
+  { key: 'PENDING', label: '待支付' },
+  { key: 'COMPLETED', label: '已完成' },
+  { key: 'CANCELLED', label: '已取消' },
+  { key: 'EXPIRED', label: '已超时' },
+];
+
+export function detectDeviceIsMobile(): boolean {
+  if (typeof window === 'undefined') return false;
+
+  const ua = navigator.userAgent || '';
+  const mobileUA = /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Windows Phone|Mobile/i.test(ua);
+  const smallPhysicalScreen = Math.min(window.screen.width, window.screen.height) <= 768;
+  const touchCapable = navigator.maxTouchPoints > 1;
+
+  return mobileUA || (touchCapable && smallPhysicalScreen);
+}
+
+export function formatStatus(status: string): string {
+  return STATUS_TEXT_MAP[status] || status;
+}
+
+export function formatCreatedAt(value: string): string {
+  const date = new Date(value);
+  if (Number.isNaN(date.getTime())) return value;
+  return date.toLocaleString();
+}
+
+export function getStatusBadgeClass(status: string, isDark: boolean): string {
+  if (['COMPLETED', 'PAID'].includes(status)) {
+    return isDark ? 'bg-emerald-500/20 text-emerald-200' : 'bg-emerald-100 text-emerald-700';
+  }
+  if (status === 'PENDING') {
+    return isDark ? 'bg-blue-500/20 text-blue-200' : 'bg-blue-100 text-blue-700';
+  }
+  if (['CANCELLED', 'EXPIRED', 'FAILED'].includes(status)) {
+    return isDark ? 'bg-slate-600 text-slate-200' : 'bg-slate-100 text-slate-700';
+  }
+  return isDark ? 'bg-slate-700 text-slate-200' : 'bg-slate-100 text-slate-700';
+}