Add request ID propagation to server logs and responses

[fantaJinMode]

Description

Attaches a unique request ID to every HTTP request, honoring inbound x-request-id headers and echoing the ID back in responses. This makes distributed tracing and log correlation straightforward.

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📝 Documentation update
• ♻️ Code refactoring
• ⚡ Performance improvement
• ✅ Test addition or update

Changes Made

• Use inbound x-request-id header as the request ID when present, otherwise generate a UUID
• Added onSend hook to echo the resolved request ID back via x-request-id response header

Testing

• Tests pass locally (npm test)
• New tests added for new functionality
• Existing tests updated (if needed)
• Type checking passes (npm run typecheck)

Checklist

• My code follows the project's code style
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have used conventional commit messages (e.g., feat:, fix:)
• I have signed the Contributor License Agreement (the CLA bot will prompt you)

Breaking Changes

None

Additional Notes

Why It Was Needed

Without a consistent request ID, correlating log entries across services (or debugging a specific client request) required guesswork. Propagating and reflecting the x-request-id header is a standard observability practice.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[codecov]

Codecov Report

❌ Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/index.ts	0.00%	6 Missing ⚠️

📢 Thoughts on this report? Let us know!