Update CI workflow for multi-architecture builds and ECR integration - #56

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, docker/build-push-action@v6, docker/setup-buildx-action@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

JSONArgsRecommended: JSON arguments recommended for ENTRYPOINT to prevent unintended behavior related to OS signals More info: https://docs.docker.com/go/dockerfile/rule/json-args-recommended/