Add Lychee Doc Links Check to Local and CI (#19742)

Co-authored-by: Zijie Xia <zijie_xia@icloud.com>
Co-authored-by: Zijie Xia <zijiexia@users.noreply.github.com>
Co-authored-by: zijiexia <37504505+zijiexia@users.noreply.github.com>

.github/workflows/lint.yml

@@ -25,6 +25,11 @@ jobs:
       - name: Run pre-commit checks
         run: SKIP=no-commit-to-branch pre-commit run --all-files --show-diff-on-failure
 
+      - name: Run lychee docs checks (offline references)
+        uses: lycheeverse/lychee-action@8646ba30535128ac92d33dfc9133794bfdd9b411 # v2
+        with:
+          args: --config .github/linters/lychee.toml README.md "docs/**/*.md" "docs/**/*.rst" "docs/**/*.ipynb"
+
       - name: Run sgl-kernel clang-format checks
         uses: DoozyX/clang-format-lint-action@v0.20
         with:

.github/workflows/nightly-link-check.yml

@@ -0,0 +1,32 @@
+name: Nightly Link Check
+
+on:
+  schedule:
+    - cron: "0 2 * * *"
+  workflow_dispatch:
+
+concurrency:
+  group: nightly-link-check-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  lychee-online:
+    if: github.repository == 'sgl-project/sglang'
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Run lychee online link checks
+        uses: lycheeverse/lychee-action@8646ba30535128ac92d33dfc9133794bfdd9b411 # v2
+        with:
+          fail: true
+          args: >-
+            --config .github/linters/lychee-ci.toml
+            README.md
+            docs/**/*.md
+            docs/**/*.rst
+            docs/**/*.ipynb
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}