- Nullish coalescing (??) doesn't work with booleans as expected
- When readOnly=false, ?? never evaluates right side (!selectedNode)
- Changed to logical OR (||) for correct disabled state calculation
- Added comprehensive tests verifying the fix:
* readOnly=false with no selection: editing disabled
* readOnly=false with selection: editing enabled
* readOnly=true: editing always disabled
- Removed unused eslint-disable directive
Refs #337
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>