ci: pin Cutter actions and guard workflow-only changes (#4199)

Pin the remaining Cutter upload/download actions and enforce immutable GitHub/Docker references at actual action call sites. Run the same exact guard for workflow-only changes without preparing runtime artifacts.

Co-authored-by: Govindu Sasanka <31107592+GovinduSasanka@users.noreply.github.com>
Co-authored-by: Kaoru0822 <208281322+kaoru0822-kitauji@users.noreply.github.com>

.github/workflows/ci.yml

@@ -140,6 +140,11 @@ jobs:
       - name: Validate workflow syntax and expressions
         if: needs.changes.outputs.workflows == 'true'
         run: go run github.com/rhysd/actionlint/cmd/actionlint@v1.7.7 -shellcheck= -pyflakes=
+      # Code tiers run this source-only policy test in their existing shards.
+      # Workflow-only changes need the guard, without preparing runtime artifacts.
+      - name: Check action pins for workflow-only changes
+        if: needs.changes.outputs.workflows == 'true' && needs.changes.outputs.code != 'true'
+        run: node scripts/run-exact-tests.mjs run tests/boundary/filesystem/workflowActionPinning.test.ts
       - name: Record static task source and execution identity
         continue-on-error: true
         if: needs.changes.outputs.code == 'true'

.github/workflows/real-cutter.yml

@@ -22,7 +22,7 @@ jobs:
           sudo apt-get update
           sudo apt-get install --no-install-recommends -y g++-mingw-w64-x86-64
       - run: npm run build:windows-native
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         with:
           name: cutter-windows-native
           path: native/windows/build/
@@ -53,7 +53,7 @@ jobs:
         uses: ./.github/actions/npm-cache
       - run: npm ci
       - if: matrix.platform == 'Windows'
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4.3.0
         with:
           name: cutter-windows-native
           path: native/windows/build/
@@ -67,7 +67,7 @@ jobs:
         env:
           EXPECTED_PLATFORM: ${{ matrix.platform }}
         run: npm run verify:cutter
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
         if: always()
         with:
           name: cutter-upstream-${{ matrix.platform }}