[codex] Support standalone podman-compose discovery

[jooh]

Summary

Fixes #77.

Fixes compose container discovery for standalone podman-compose, which rejects ps -q <service> and does not support the Docker Compose ps -q -a <service> shape.

The native runtime now resolves Compose service containers through the container engine with Compose labels, matching the upstream discovery model:

• com.docker.compose.project=<project>
• com.docker.compose.service=<service>

This also avoids podman-compose rm, which is not available in standalone podman-compose 1.5.0; --remove-existing-container now removes the resolved container by engine ID.

Test Coverage

• Added fake-harness regression coverage for standalone podman-compose rejecting service args on ps.
• Added coverage that compose remove-existing uses engine rm -f <container-id>.
• Expanded the real-engine smoke script to cover both image and Compose lifecycle flows.
• Added Make targets and CI matrix coverage for Docker and standalone podman-compose.

Validation

• cargo test --manifest-path cmd/devcontainer/Cargo.toml --test runtime_container_smoke
• make tests
• make real-engine-lifecycle-smoke-docker
• make real-engine-lifecycle-smoke-podman