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
  • Added automated link validation across documentation to identify and prevent broken URLs, helping maintain documentation quality and user experience.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Pro Plus

Run ID: 56349628-b689-44e9-8241-9f8e986402f5

📥 Commits

Reviewing files that changed from the base of the PR and between ed43c3b and 2f4b935.

📒 Files selected for processing (1)

• .github/workflows/link-check.yml

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📝 Walkthrough

Walkthrough

This PR adds a new GitHub Actions workflow file that automates Markdown link validation across the repository. The link-check workflow uses the Lychee action to scan all **/*.md files for dead URLs. It triggers on pull requests, pushes to main, a weekly Monday schedule, and manual dispatch. The workflow runs on Ubuntu with read-only contents permission, includes concurrency settings, excludes mail-related links, accepts specific HTTP status codes, and is configured as non-blocking to avoid blocking merges on link failures.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description does not follow the required template structure and is missing critical required sections including Summary, Scope checkboxes, Checks, Linked issue, and Deploy impact.	Reformat the description to match the repository template with all required sections (Summary, Scope, Checks, Linked issue, Deploy impact) and appropriate checkboxes marked.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'ci: add link-check workflow (lychee)' is concise, specific, and clearly summarizes the main change—adding a CI workflow for link checking.
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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_{Comment @coderabbitai help to get the list of available commands and usage tips.}