azd ai rle extension enhancements

## Scope

### Use Podman for local environments

- Replace the Docker Desktop dependency used by local `init`/`run` workflows with Podman.
- Update prerequisite checks, process execution, error messages, tests, and documentation accordingly.

### Use ACR remote builds during publishing

- Replace the local container build and push performed by `azd ai rle publish` with an Azure Container Registry remote build.
- Continue registering the resulting image with the RLE control plane after the build succeeds.
- Surface actionable authentication, registry, build, and image-registration failures.

### Tracing / Logs

- for debugging issues, etc.

## Acceptance criteria

- [ ] Local environment build/run uses Podman and no longer requires Docker Desktop.
- [ ] Publishing uses an ACR remote build rather than building and pushing locally.
- [ ] README and prerequisite documentation reflect Podman and ACR remote-build requirements.
- [ ] Relevant extension tests, linting, and cross-platform builds pass.

Start with the azd ai rle init/run and publish workflows, then review the prerequisite checks, process execution, error handling, and existing extension tests. Update the README and prerequisite documentation alongside the workflow changes, and consider the work done when Podman local runs, ACR remote publishing and image registration work with actionable failures and the tests, linting, and cross-platform builds pass.

Written by the indexing model from the issue text.