ci: robust health check with retries; normalize IMAGE_NAME in publish workflow

.github/workflows/docker-publish.yml

@@ -29,6 +29,11 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@08eba0b27e820071cde6df949e0beb9ba4906955 # v4
 
+      - name: Normalize image name
+        run: |
+          raw="${{ github.repository_owner }}/${{ github.event.repository.name }}"
+          echo "IMAGE_NAME=$(echo "$raw" | tr '[:upper:]' '[:lower:]')" >> $GITHUB_ENV
+
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@e468171a9de216ec08956ac3ada2f0791b6bd435 # v3