fix: add repository.url for npm provenance publishing

[justinchung-cb]

Summary

• Add repository field to package.json with the GitHub repo URL

Details

npm trusted publishing with sigstore provenance requires repository.url in package.json to match the GitHub repo URL. Without it, the publish fails with:

Error verifying sigstore provenance bundle: Failed to validate repository information: package.json: "repository.url" is "", expected to match "https://github.com/coinbase/onchaintestkit"

Test Plan

• Merge this PR
• Run the Release (manual) workflow
• Verify npm view @coinbase/onchaintestkit version shows 1.2.1

Made with Cursor

[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