- Optimistic tree updates: new file/folder/diagram shows up instantly
- Column types fix: manifest.py writes 'unknown' instead of silently
  defaulting to 'string' when dbt data_type is absent
- Diagram-level relationships persist: top-level relationships[] in
  .diagram.yaml, merged by adaptDiagramYaml
- Four relationship entry points: toolbar, inspector, command palette,
  right-click menu
- Identifying vs non-identifying edges, tooltips on CHK/DEF/IDX, enum
  badge, NN across all views