Replace widget panels with simulation.js as main visualization

[wildone]

Task Summary\n- Replace widget.js panel-based architecture with simulation.js as the main visualization\n- Remove dependencies on Tree, Filter, Promo, Scratch panels\n- Implement event-based data loading using /viz-data/overview-default-incident\n- Add reload functionality\n\n## Acceptance Criteria\n- [ ] simulation.js uses postMessage event mechanism for data loading\n- [ ] Supports both local and widget modes\n- [ ] Uses dataUrl: /viz-data/overview-default-incident\n- [ ] Reload functionality implemented (button to be added later)\n- [ ] All panel dependencies removed from main entry point\n\n## Implementation Plan\n1. Update simulation.js to use event system (raiseEventDataRequest, windowListener)\n2. Remove hardcoded data file, use dynamic data from events\n3. Add mode detection (local vs widget)\n4. Add reload functionality\n5. Update widget.js or entry point to use simulation instead of panels\n6. Test event communication and data loading