feat: add explicit Node.js engine requirement to package.json

[faisalnugroho]

Summary\n\nAdds an explicit engines field to the root package.json specifying Node.js >= 22 and pnpm >= 10 requirements.\n\n## Changes\n\n- Added engines.node: ">=22" (aligned with existing .nvmrc)\n- Added engines.pnpm: ">=10" (aligned with packageManager field)\n\n## Motivation\n\nThe repository defines Node.js tooling through .nvmrc and package manager configuration, but does not expose an explicit engines requirement inside package.json. Adding this field improves contributor onboarding and makes version expectations clearer.\n\nCloses #2652

[cb-heimdall]

🟡 Heimdall Review Status

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Reviews	🟡 0/1	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 1 Sum 2

[vercel]

@faisalnugroho is attempting to deploy a commit to the Coinbase Team on Vercel.

A member of the Team first needs to authorize it.

[faisalnugroho]

Hi! Following up on this improvement PR. This PR adds an explicit Node.js engine requirement to package.json to prevent version mismatch issues that cause cryptic build errors.

All CI checks pass (StepSecurity ✅). Would love to get your review when you have a moment. Thanks!

[faisalnugroho]

Hi! I'd love to get this PR reviewed when you have a moment. This PR addresses add explicit Node.js engine requirement. Happy to make any adjustments based on your feedback. Thank you!