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/components/OrderFilterBar.tsx

@@ -0,0 +1,29 @@
+import { FILTER_OPTIONS, type OrderStatusFilter } from '@/lib/pay-utils';
+
+interface OrderFilterBarProps {
+  isDark: boolean;
+  activeFilter: OrderStatusFilter;
+  onChange: (filter: OrderStatusFilter) => void;
+}
+
+export default function OrderFilterBar({ isDark, activeFilter, onChange }: OrderFilterBarProps) {
+  return (
+    <div className="flex flex-wrap gap-2">
+      {FILTER_OPTIONS.map((item) => (
+        <button
+          key={item.key}
+          type="button"
+          onClick={() => onChange(item.key)}
+          className={[
+            'rounded-full border px-3 py-1.5 text-xs font-medium transition-colors',
+            activeFilter === item.key
+              ? (isDark ? 'border-slate-500 bg-slate-700 text-slate-100' : 'border-slate-400 bg-slate-900 text-white')
+              : (isDark ? 'border-slate-600 text-slate-300 hover:bg-slate-800' : 'border-slate-300 text-slate-600 hover:bg-slate-100'),
+          ].join(' ')}
+        >
+          {item.label}
+        </button>
+      ))}
+    </div>
+  );
+}