fix(openbis): ✨ DAG-aware registration with parent/child provenance
- register_in_openbis.py: rewrite to parse dvc.yaml, topo-sort stages, upload one RAW_DATA dataset per stage, wire parents= from the DVC dep graph, set PARENT_PERMIDS property, second pass sets native children relationships; foreach stages expand to name@item
- openbis_setup_schema.py: replace SOURCE_FILE with STAGE_NAME, add PARENT_PERMIDS property, add update-on-exists logic for labels
- docker-compose.yml: upgrade openbis-app to 6.8.1 (native arm64, no platform override needed)
- CLAUDE.md: document completed work and stale-token gotcha