[BuildImage] build-image / remove-image CLI (Docker + Podman)

[pyadav]

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#1

What to build

Provider-namespaced CLI commands for image lifecycle:

• sanddune docker build-image / sanddune podman build-image — rebuild the image from an existing .sanddune/ (run after editing the Dockerfile/Containerfile)
• sanddune docker remove-image / sanddune podman remove-image — remove the image (free disk space)

build-image accepts --dockerfile <path> (Docker) or --containerfile <path> (Podman) to point at a custom file with build context = cwd. All four commands accept --image-name (default sanddune:<repo-dir-name>).

Acceptance criteria

• sanddune docker build-image rebuilds the Docker image from .sanddune/Dockerfile
• sanddune podman build-image rebuilds the Podman image from .sanddune/Containerfile
• --dockerfile <path> (Docker only) and --containerfile <path> (Podman only) point at custom files; build context = current working directory
• sanddune docker remove-image and sanddune podman remove-image remove the named image
• All four commands accept --image-name (default sanddune:<repo-dir-name>)
• CLI subcommands are nested under provider namespace (docker / podman); unknown subcommands print actionable help
• Unit tests: argv parsing for each command and flag combination
• Smoke tests (CI-flag-gated): build → remove cycle for both Docker and Podman against a fixture Dockerfile/Containerfile
• bun test and bun run typecheck pass

Blocked by

• [Init] sanddune init CLI — Docker + blank template #21