Clean up GCS fork: minimal changeset vs upstream actions/cache

Realign the fork so it diffs from upstream actions/cache only by the GCS
cache backend, instead of carrying unrelated downgrades and deletions.

- Restore package.json/package-lock.json to upstream 5.0.4 deps; the fork
  had downgraded to 4.2.x. Re-add @google-cloud/storage (gcsCache.ts needs it).
- Rebuild dist/ against the restored deps so it bundles the real GCS client
  rather than a stale build against downgraded deps.
- Restore deleted upstream files: 7 workflow YAMLs, .github/CODEOWNERS,
  .licensed.yml. (To be disabled in the fork, not removed.)
- Revert action.yml/restore/save manifests to upstream name/description/
  author; keep only the gcs-bucket/gcs-path-prefix inputs as the fork diff.
- auto-tag.yml: track upstream's highest semver release tag, moving both the
  exact-version tag and the major alias, instead of force-pinning v1.
- Remove checkout/ composite action; relocated to Cula-Technologies/checkout.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.github/workflows/licensed.yml

@@ -0,0 +1,43 @@
+name: License check
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  validate-cached-dependency-records:
+    runs-on: ubuntu-latest
+    name: Check licenses
+    steps:
+
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Install dependencies
+        run: npm ci --ignore-scripts
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: '3.1.7'
+
+      - name: Install licensed tool
+        run: |
+          cd "$RUNNER_TEMP"
+          curl -Lfs -o licensed.tar.gz https://github.com/licensee/licensed/archive/refs/tags/v5.0.4.tar.gz
+          tar -xzf licensed.tar.gz
+          cd licensed-5.0.4
+          bundle install
+
+      - name: Check cached dependency records
+        run: |
+          cd ${{ github.workspace }}
+          BUNDLE_GEMFILE=$RUNNER_TEMP/licensed-5.0.4/Gemfile bundle exec $RUNNER_TEMP/licensed-5.0.4/exe/licensed status