feat: Add lychee-action to check for broken links (#11781)

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

.github/workflows/ci.yml

@@ -93,6 +93,17 @@ jobs:
       - name: 'Run sensitive keyword linter'
         run: 'node scripts/lint.js --sensitive-keywords'
 
+  link_checker:
+    name: 'Link Checker'
+    runs-on: 'ubuntu-latest'
+    steps:
+      - name: 'Checkout'
+        uses: 'actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8' # ratchet:actions/checkout@v5
+      - name: 'Link Checker'
+        uses: 'lycheeverse/lychee-action@885c65f3dc543b57c898c8099f4e08c8afd178a2' # ratchet: lycheeverse/lychee-action@v2.6.1
+        with:
+          args: '--verbose ./**/*.md'
+          fail: true
   test_linux:
     name: 'Test (Linux)'
     runs-on: 'gemini-cli-ubuntu-16-core'
@@ -354,6 +365,7 @@ jobs:
     if: 'always()'
     needs:
       - 'lint'
+      - 'link_checker'
       - 'test_linux'
       - 'test_mac'
       - 'codeql'
@@ -363,6 +375,7 @@ jobs:
       - name: 'Check all job results'
         run: |
           if [[ (${{ needs.lint.result }} != 'success' && ${{ needs.lint.result }} != 'skipped') || \
+               (${{ needs.link_checker.result }} != 'success' && ${{ needs.link_checker.result }} != 'skipped') || \
                (${{ needs.test_linux.result }} != 'success' && ${{ needs.test_linux.result }} != 'skipped') || \
                (${{ needs.test_mac.result }} != 'success' && ${{ needs.test_mac.result }} != 'skipped') || \
                (${{ needs.codeql.result }} != 'success' && ${{ needs.codeql.result }} != 'skipped') || \

.github/workflows/links.yml

@@ -0,0 +1,23 @@
+name: 'Links'
+
+on:
+  push:
+    branches: ['main']
+  pull_request:
+    branches: ['main']
+  repository_dispatch:
+  workflow_dispatch:
+  schedule:
+    - cron: '00 18 * * *'
+
+jobs:
+  linkChecker:
+    runs-on: 'ubuntu-latest'
+    steps:
+      - uses: 'actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8' # ratchet:actions/checkout@v5
+
+      - name: 'Link Checker'
+        id: 'lychee'
+        uses: 'lycheeverse/lychee-action@885c65f3dc543b57c898c8099f4e08c8afd178a2' # ratchet: lycheeverse/lychee-action@v2.6.1
+        with:
+          args: '--verbose --no-progress ./**/*.md'