Restructure prov:wasGeneratedBy as typed activity list (Collection / Preprocessing / Annotation)

Add sha256 to FileObjects; ISO 8601 dataCollectionTimeFrame

Update croissant: HF contentUrls, RAI fields, conformsTo 1.1

Add HF dataset card YAML frontmatter (configs, license, tags)

Initial PRAXIS release for NeurIPS 2026 ED-track

initial commit