ci: add link-check workflow (lychee)

[satyakwok]

Same pattern as the link-check workflow already shipped to awesome-sentrix, whitepaper, canonical-contracts, and dapp-starter. Lychee scans every markdown link on PR + push to main + weekly Monday 03:00 UTC cron. Non-blocking — mirrors the gitleaks workflow's policy.

Summary by CodeRabbit

• Chores
  • Introduced automated link validation for documentation, triggered on pull requests, weekly schedule, and manual dispatch.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 5dc4546e-1efc-41f4-bc5d-8fe1b08f2549

📥 Commits

Reviewing files that changed from the base of the PR and between e047cc1 and 425bddb.

📒 Files selected for processing (1)

• .github/workflows/link-check.yml

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📝 Walkthrough

Walkthrough

This pull request adds a new GitHub Actions workflow file that enables automated link validation across the repository. The link-check workflow triggers on pull requests, pushes to the main branch, a weekly Monday schedule, and manual dispatch. It uses the Lychee link checker action to scan Markdown files, with an allowlist of acceptable HTTP status codes and concurrency controls. The workflow is configured as non-blocking—link check failures do not fail the build.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~5 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is incomplete; it lacks the required template sections including explicit Summary, Test plan, and Related sections as specified in the repository template.	Restructure the description to follow the template with dedicated Summary, Test plan (with test cases), and Related sections for clarity and consistency.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately and concisely describes the main change: adding a CI workflow for link checking using lychee.
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.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ci/link-check

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