A custom action needs Python and several native Linux packages in a controlled userspace. The author wants its dependencies packaged with the action instead of installed separately by every consumer workflow. Which implementation is the best match?

1. Use a JavaScript action with no packaging and assume Python packages exist on all runners.
2. Use a Docker container action with a Dockerfile and appropriate entrypoint.
3. Use a workflow template only and assume it distributes a fixed container image automatically.
4. Use a composite action and assume runs.using: composite creates an isolated operating system image.