Push stable tags as plain images instead of manifest lists (#253)

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

Author: davdhacs

.github/workflows/promote-stable.yaml

@@ -7,6 +7,10 @@ on:
         description: "Version to promote (e.g. 0.5.7). Defaults to 'latest'."
         required: false
         default: "latest"
+      target:
+        description: "Target tag suffix (e.g. 'stable', 'stable-test'). Defaults to 'stable'."
+        required: false
+        default: "stable"
 
 env:
   QUAY_STACKROX_IO_RW_USERNAME: ${{ secrets.QUAY_STACKROX_IO_RW_USERNAME }}
@@ -18,14 +22,16 @@ jobs:
     steps:
       - name: Log in to Quay
         run: |
-          docker login -u "$QUAY_STACKROX_IO_RW_USERNAME" --password-stdin <<<"$QUAY_STACKROX_IO_RW_PASSWORD" quay.io
+          skopeo login -u "$QUAY_STACKROX_IO_RW_USERNAME" --password-stdin <<<"$QUAY_STACKROX_IO_RW_PASSWORD" quay.io
       - name: Retag all flavors as stable
         run: |
           VERSION="${{ inputs.version }}"
           VERSION="${VERSION:-latest}"
           for flavor in scanner-build scanner-test stackrox-build stackrox-test stackrox-ui-test jenkins-plugin; do
             SRC="quay.io/stackrox-io/apollo-ci:${flavor}-${VERSION}"
-            DST="quay.io/stackrox-io/apollo-ci:${flavor}-stable"
+            TARGET="${{ inputs.target }}"
+            TARGET="${TARGET:-stable}"
+            DST="quay.io/stackrox-io/apollo-ci:${flavor}-${TARGET}"
             echo "Promoting ${SRC} → ${DST}"
-            docker buildx imagetools create --tag "${DST}" "${SRC}"
+            skopeo copy "docker://${SRC}" "docker://${DST}"
           done