sysml-bench v0.1.1: CI fix — buildah container build, decoupled publish jobs

Fixes:
- Replace docker-in-docker with buildah for podman runner compatibility
- Decouple publish stages so PyPI, container, and HF dataset run in parallel
- Container: registry.gitlab.com/nomograph/sysml-bench:v0.1.1
- pip install sysml-bench==0.1.1