✨ CI Upgrade: Introduce Docs Link Guard to squash broken links & typos

[xam-dev-ux]

Why this matters

• Eliminates recurring PRs fixing outdated Base Learn URLs (/base-learn/... → /learn/)
• Adds a zero-dependency script + GitHub Action for automated validation
• Improves contributor experience and keeps docs clean

What is included

• tools/ci/guard-docs-links.mjs — scans Markdown/MDX (and optionally TS/TSX) for outdated docs URLs and common typos
• .github/workflows/docs-link-guard.yml — runs the check on PRs that touch docs/web
• README updated with clear instructions

Common broken URL patterns (with examples)

1. Old Base Learn path → New Learn path
   Before: https://docs.base.org/base-learn/docs/welcome/
   https://docs.base.org/base-learn/arrays/arrays-exercise/
   After: https://docs.base.org/learn/welcome/
   https://docs.base.org/learn/arrays/arrays-exercise/

2. Trailing /docs/ carried over by mistake
   Before: https://docs.base.org/learn/docs/welcome/
   After: https://docs.base.org/learn/welcome/

3. Cloudflare constant typo
   Before: CLOUDFARE_IPFS_PROXY
   After: CLOUDFLARE_IPFS_PROXY

How to test

yarn lint:links:check
yarn lint:links:fix

[vercel]

@xamaitena is attempting to deploy a commit to the Coinbase Team on Vercel.

A member of the Team first needs to authorize it.

[cb-heimdall]

🟡 Heimdall Review Status

Requirement	Status	More Info
Reviews	🟡 0/2	Denominator calculation Show calculation 1 if user is bot 0 1 if user is external 0 2 if repo is sensitive 0 From .codeflow.yml 1 Additional review requirements Show calculation Max 0 0 From CODEOWNERS 0 Global minimum 0 Max 1 1 1 if commit is unverified 1 Sum 2