Add GitHub workflow to build init-cassandra image

.github/workflows/deploy-init-cassandra.yml

@@ -0,0 +1,24 @@
+name: Init-Cassandra Pipeline
+
+on:
+  push:
+
+  build-and-deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+      - name: Log in to Docker Container Registry
+        uses: docker/login-action@v3
+        with:
+          username: ${{ secrets.DOCKER_USERNAME }}
+          password: ${{ secrets.DOCKER_PASSWORD }}
+      - name: Build and push multi-arch Docker image
+        run: |
+          docker buildx build \
+            --file init-cassandra.Dockerfile
+            --platform linux/amd64,linux/arm64 \
+            --tag explorviz/init-cassandra:latest . \
+            --push