Migrate all 293 class files to ontology-aligned slots
Extends migration to all class types (museums, libraries, galleries, etc.)
New slots added to class_metadata_slots.yaml:
- RiC-O: rico_record_set_type, rico_organizational_principle,
rico_has_or_had_holder, rico_note
- Multilingual: label_de, label_es, label_fr, label_nl, label_it, label_pt
- Scope: scope_includes, scope_excludes, custodian_only,
organizational_level, geographic_restriction
- Notes: privacy_note, preservation_note, legal_note
Migration script now handles 30+ annotation types.
All migrated schemas pass linkml-validate.
Total: 387 class files now use proper slots instead of annotations.
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