SHA-pin GitHub Actions and upgrade deprecated checkout versions

- Upgrade actions/checkout from v2/v3 to SHA-pinned v4
- SHA-pin all unshelled action tags (pages, CodeQL, scorecard,
  rust-cache, upload/download-artifact, setup-node, cache)
- Standardise scorecard-action to v2.4.0
- Fix setup-node@v6 → SHA-pinned v4

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

.github/workflows/jekyll-gh-pages.yml

@@ -28,7 +28,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
       - name: Setup Pages
         uses: actions/configure-pages@983d7736d9b0ae728b81ab479565c72886d7745b # v5
       - name: Build with Jekyll
@@ -37,7 +37,7 @@ jobs:
           source: ./
           destination: ./_site
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v4
+        uses: actions/upload-pages-artifact@56afc609e74202658d3ffba0e8f6dda462b719fa # v4
 
   # Deployment job
   deploy:

.github/workflows/jekyll.yml

@@ -33,7 +33,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v6.0.1
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
       - name: Setup Ruby
         # https://github.com/ruby/setup-ruby/releases/tag/v1.207.0
         uses: ruby/setup-ruby@708024e6c902387ab41de36e1669e43b5ee7085e
@@ -51,7 +51,7 @@ jobs:
           JEKYLL_ENV: production
       - name: Upload artifact
         # Automatically uploads an artifact from the './_site' directory by default
-        uses: actions/upload-pages-artifact@v4
+        uses: actions/upload-pages-artifact@56afc609e74202658d3ffba0e8f6dda462b719fa # v4
 
   # Deployment job
   deploy:

ipv6-only/.github/workflows/ci.yml

@@ -16,7 +16,7 @@ jobs:
         rust: [stable, beta]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
 
     - name: Setup Rust ${{ matrix.rust }}
       uses: dtolnay/rust-action@stable
@@ -25,7 +25,7 @@ jobs:
         components: rustfmt, clippy
 
     - name: Cache cargo
-      uses: actions/cache@v4
+      uses: actions/cache@5a3ec84eff668545956fd18022155c47e93e2684 # v4
       with:
         path: |
           ~/.cargo/bin/
@@ -52,7 +52,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
 
     - name: Run ShellCheck
       uses: ludeeus/action-shellcheck@master
@@ -65,7 +65,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
 
     - name: Install Nickel
       run: |
@@ -82,7 +82,7 @@ jobs:
     needs: [rust]
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
 
     - name: Build container image
       run: |
@@ -100,7 +100,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
 
     - name: Setup Rust
       uses: dtolnay/rust-action@stable
@@ -116,7 +116,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
 
     - name: Verify no banned files
       run: |

ipv6-only/.github/workflows/container-policy.yml

@@ -5,7 +5,7 @@ jobs:
   check:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
       - name: Enforce container policy
         run: |
           # Block new Dockerfiles

ipv6-only/.github/workflows/jekyll-gh-pages.yml

@@ -28,16 +28,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
       - name: Setup Pages
-        uses: actions/configure-pages@v5
+        uses: actions/configure-pages@983d7736d9b0ae728b81ab479565c72886d7745b # v5
       - name: Build with Jekyll
-        uses: actions/jekyll-build-pages@v1
+        uses: actions/jekyll-build-pages@44a6e6beabd48582f863aeeb6cb2151cc1716697 # v1
         with:
           source: ./
           destination: ./_site
       - name: Upload artifact
-        uses: actions/upload-pages-artifact@v3
+        uses: actions/upload-pages-artifact@56afc609e74202658d3ffba0e8f6dda462b719fa # v3
 
   # Deployment job
   deploy:
@@ -49,4 +49,4 @@ jobs:
     steps:
       - name: Deploy to GitHub Pages
         id: deployment
-        uses: actions/deploy-pages@v4
+        uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac5b3c0c03e # v4

ipv6-only/.github/workflows/rust-ci.yml

@@ -9,11 +9,11 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: rustfmt, clippy
-      - uses: Swatinem/rust-cache@v2
+      - uses: Swatinem/rust-cache@779680da715d629ac1d338a641029a2f4372abb5 # v2
 
       - name: Check formatting
         run: cargo fmt --all -- --check
@@ -30,7 +30,7 @@ jobs:
   security:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
       - uses: dtolnay/rust-toolchain@stable
       - name: Install cargo-audit
         run: cargo install cargo-audit
@@ -42,7 +42,7 @@ jobs:
   coverage:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4
       - uses: dtolnay/rust-toolchain@stable
       - name: Install tarpaulin
         run: cargo install cargo-tarpaulin