PaymentRequest

{
    "appId": "app_123",
    "orderId": "order_12345",
    "type": "exactIn",
    "display": {
        "title": "Order #12345",
        "description": "string",
        "currency": "USD"
    },
    "source": {
        "chainId": "1",
        "tokenSymbol": "ETH",
        "tokenAddress": "string",
        "amount": "100.00"
    },
    "destination": {
        "chainId": "1",
        "receiverAddress": "GDFLZTLVMLR3OVO4VSODYB7SGVIOI2AS652WODBCGBUQAMKQL6O3QYPU",
        "receiverMemo": "string",
        "tokenSymbol": "ETH",
        "tokenAddress": "string",
        "amount": "100.00"
    },
    "webhookUrl": "https://your-domain.com/webhook",
    "webhookSecret": "whsec_abc123...",
    "metadata": {}
}