托管结账（自托管集成）

const res = await fetch('https://api.puffinmoney.com/v1/gateway/api/payment-intents', {
  method: 'POST',
  headers: { 'X-API-Key': process.env.PUFFIN_KEY, 'Content-Type': 'application/json' },
  body: JSON.stringify({
    amount: '99.00',
    token: 'USDC_BASE',
    chain: 'BASE',
    successUrl: 'https://yourstore.com/orders/123/thanks',
    metadata: { orderId: '123' },
  }),
});
const { intent, checkoutUrl } = await res.json();

GET /v1/gateway/api/payment-intents/:id   # X-API-Key