Build amd64 and arm64 in parallel with native runners

- Use ubuntu-22.04-arm for native arm64 builds (no QEMU)
- Run amd64 and arm64 builds in parallel
- Keep short SHA format (7 chars) for image tags

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: csenet

.github/workflows/image-build.yml

@@ -11,18 +11,11 @@ env:
 jobs:
   build-amd64:
     runs-on: ubuntu-latest
-    outputs:
-      image_tag: ${{ steps.tag.outputs.IMAGE_TAG }}
     steps:
       - uses: actions/checkout@v4
       - uses: docker/setup-buildx-action@v3
       - name: Set tag
-        id: tag
-        run: |
-          export TIMESTAMP=$(date +%s)
-          export SHA=$(echo ${{ github.sha }} | cut -c1-7)
-          echo "IMAGE_TAG=$SHA-$TIMESTAMP" >> $GITHUB_OUTPUT
-          echo "IMAGE_TAG=$SHA-$TIMESTAMP" >> $GITHUB_ENV
+        run: echo "IMAGE_TAG=$(echo ${{ github.sha }} | cut -c1-7)-${{ github.run_id }}" >> $GITHUB_ENV
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
         with:
@@ -42,12 +35,11 @@ jobs:
 
   build-arm64:
     runs-on: ubuntu-22.04-arm
-    needs: build-amd64
-    env:
-      IMAGE_TAG: ${{ needs.build-amd64.outputs.image_tag }}
     steps:
       - uses: actions/checkout@v4
       - uses: docker/setup-buildx-action@v3
+      - name: Set tag
+        run: echo "IMAGE_TAG=$(echo ${{ github.sha }} | cut -c1-7)-${{ github.run_id }}" >> $GITHUB_ENV
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
         with:
@@ -68,9 +60,9 @@ jobs:
   merge:
     runs-on: ubuntu-latest
     needs: [build-amd64, build-arm64]
-    env:
-      IMAGE_TAG: ${{ needs.build-amd64.outputs.image_tag }}
     steps:
+      - name: Set tag
+        run: echo "IMAGE_TAG=$(echo ${{ github.sha }} | cut -c1-7)-${{ github.run_id }}" >> $GITHUB_ENV
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
         with: