2026 01 28 Add Code Drawing Node

<!-- entry: {"id":"2026-01-28-28-3-code-drawing-inline-mermaid-plantuml-graphviz-605121a0","kind":"new","migrationNotes":[]} -->

• code-drawing-kit, code-drawing-base-kit, code-drawing-node, code-drawing-demo: Add inline code drawing for Mermaid, PlantUML, Graphviz, and Flowchart diagrams.

<!-- entry: {"id":"2026-01-28-28-3-editor-register-code-drawing-kits-b61b770d","kind":"wiring","migrationNotes":["Register code drawing in editor kits, insert actions, slash actions, block menu actions, and transforms."]} -->

• editor-kit, block-context-menu, insert-toolbar-button, slash-node, turn-into-toolbar-button, transforms: Register code drawing in editor kits, insert actions, slash actions, block menu actions, and transforms.