Move legend and namespace note into a standalone notations.drawio file
shared across all figures. Regenerate Step 6 figures with stacked
datatype property boxes (UML-like) matching the Step 5 style, instead
of separate connected nodes.
Ontology overview diagram shows all tm: classes, object/datatype
properties, schema:/org:/skos: external classes, subClassOf
relationships, and namespace color coding using Chowlk notation.
Example subgraph diagram shows Irene Abendroth instance data with
representative memberships, migrations, relationships, and places.
Includes Chowlk library for draw.io.
