docs: update README with unit testing, Lighthouse CI, and security headers

[chongruei]

Summary

• Fix the stale Node.js requirement in the README (>=20.9.0 → >=24.0.0, matching engines in package.json) and note the pnpm version floor
• Add feature bullets for unit testing (100% coverage), Lighthouse CI, and security headers, which were added in recent PRs but never reflected in the README
• Add "Run Unit Tests" and "Run Lighthouse CI" sections documenting pnpm test:unit and pnpm test:lighthouse

Test plan

• Docs-only change; no code paths affected

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Generated by Claude Code

Summary by CodeRabbit

• Documentation
  • Documented built-in unit testing with full coverage.
  • Added Lighthouse CI and Core Web Vitals budget guidance.
  • Documented security header capabilities.
  • Updated minimum Node.js and pnpm requirements.
  • Added instructions for running unit tests and Lighthouse CI checks.

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Project	Deployment	Actions	Updated (UTC)
next-app-boilerplate	Ready	Preview, Comment	Jul 13, 2026 1:18pm

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 4dc7923a-cb0c-4176-a606-99167f150d2d

📥 Commits

Reviewing files that changed from the base of the PR and between fb75f11 and 566f668.

📒 Files selected for processing (1)

• README.md

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📝 Walkthrough

Walkthrough

README.md now describes expanded project capabilities, updated Node.js and pnpm requirements, and commands for running unit tests and Lighthouse CI.

Changes

README documentation

Layer / File(s)	Summary
Capabilities and requirements README.md	Adds unit testing, Lighthouse CI, and security headers to the capability list, and raises the minimum Node.js and pnpm versions.
Test and Lighthouse CI instructions README.md	Documents Node’s built-in test runner, enforced coverage, Lighthouse configuration, and the commands for running both checks.

Estimated code review effort: 1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately reflects the README documentation updates for unit testing, Lighthouse CI, and security headers.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/readme-update-afjdzv

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