Fetch Sentry Risk Buyer Quickstart

Official x402 buyer flow:
- Install client packages: npm install @x402/fetch @x402/evm @x402/core viem
- Fund an EVM wallet with Base USDC.
- Set EVM_PRIVATE_KEY in your environment.

Example paid endpoint:
https://risk.fetch-sentry.online/wallet-batch?addresses=0x5e8114643966b7fd7d5cfdd8695ffc5c51ff32c0,0xce56d20689d836ec7a728ceb94a15746696c16e6&contract=0xcbb7c0000ab88b473b1f5afd9ef808440eed33bf&chain=base

Minimal TypeScript flow:
1. import { wrapFetchWithPayment } from '@x402/fetch'
2. import { x402Client, x402HTTPClient } from '@x402/core/client'
3. import { ExactEvmScheme } from '@x402/evm/exact/client'
4. import { privateKeyToAccount } from 'viem/accounts'
5. create signer from EVM_PRIVATE_KEY
6. register eip155:* with ExactEvmScheme
7. call wrapFetchWithPayment(fetch, client)
8. fetch the paid URL and read the JSON response
9. optionally inspect PAYMENT-RESPONSE via x402HTTPClient

Full example source: https://risk.fetch-sentry.online/buyer-example.ts
Official docs:
- https://docs.x402.org/getting-started/quickstart-for-buyers
- https://docs.x402.org/guides/mcp-server-with-x402

Expected result:
- First request auto-pays after HTTP 402
- Response body contains the paid risk data
- PAYMENT-RESPONSE header contains settlement info