fix(x402-fetch): allow optional fetch request init config

[0xRAG]

Description

fetch's request init param is optional.

Tests

This was tested by building the package and installing into a standalone app with the following code:

import { useX402 } from "@coinbase/cdp-hooks";

const { fetchWithPayment } = useX402();
const response = await fetchWithPayment(resourceUrl);

Checklist

• I have formatted and linted my code
• All new and existing tests pass
• My commits are signed (required for merge) -- you may need to rebase if you initially pushed unsigned commits

[cb-heimdall]

✅ Heimdall Review Status

Requirement	Status	More Info
Reviews	✅ 1/1	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 0 Sum 1

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Project	Deployment	Preview	Comments	Updated (UTC)
x402	Ready	Preview	Comment	Nov 20, 2025 6:39pm

[cb-heimdall]

Review Error for CarsonRoscoe @ 2025-11-20 18:52:50 UTC
User failed mfa authentication, see go/mfa-help

[avidreder]

LGTM