Add behavior object creation button in Properties Panel

[anchapin]

Summary

Missing UI component to create behavior objects in the editor properties panel.

Location

frontend/src/components/Editor/PropertiesPanel/PropertiesPanel.tsx:159

Context

<span className="property-value">
  No behavior defined.
  {/* TODO: Add button to create behavior object */}
</span>

Requirements

• Add button to create new behavior objects
• Integrate with behavior object creation workflow
• Update UI to show created behaviors
• Ensure proper state management

Priority

Medium - UI/UX enhancement for editor functionality