feat(ci): 👷 Add Codecov coverage reporting

[haskou]

Changes

• Match the @haskou/value-objects CI pattern with Node 24.18.0, Yarn caching, and a combined lint and coverage step.
• Upload coverage/lcov.info through codecov-action@v5 while retaining the metrics export and tarball checks.
• Add the Codecov badge, link the published documentation, and document the release branches.
• Ignore .npmrc so local configuration and tokens cannot enter Git.

Motivation

The repository generated coverage without sending it to Codecov. The README also omitted the release branch convention and linked the documentation through a repository path.

Impact

CI sends each coverage report to Codecov through the CODECOV_TOKEN secret. A Codecov outage will not block the pipeline.

Merging this feat/* branch triggers the corresponding minor release.

Validation

• yarn format:check
• yarn test:coverage: 39 suites, 81 tests, and 100% coverage
• yarn test:package
• yarn pages:build

[codecov]

Welcome to Codecov 🎉

Once you merge this PR into your default branch, you're all set! Codecov will compare coverage reports and display results in all future pull requests.

ℹ️ You can also turn on project coverage checks and project coverage reporting on Pull Request comment

Thanks for integrating Codecov - We've got you covered ☂️

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: ba2d427c6f

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".

[chatgpt-codex-connector]

Keep CI coverage for the supported Node floor

In .github/workflows/ci.yml's test job, pinning the only validation lane to Node 24.18.0 means changes can now merge without running any build, typecheck, or package-entrypoint check on Node 22, even though package.json still declares "node": ">=22" and the installation docs say the package supports Node.js 22 and newer. For regressions that only affect the minimum supported runtime, CI will stay green; keep a Node 22 lane (even just the previous build && test:typecheck path) or narrow the advertised support.

Useful? React with 👍 / 👎.