feat: 3+ panel support #39
Description
Summary
Support more than 2 code panels for Bad/Good/Better comparisons.
Motivation
Users want to show progression or multiple alternatives.
Implementation
- Dynamic panel count (2-4)
- Custom indicator for each panel
- Layout adapts to panel count
- Export handles multiple panels
UI Considerations
- Add panel button
- Remove panel button
- Horizontal scroll for many panels
Acceptance Criteria
- Add up to 4 panels
- Each panel has custom indicator
- Layout adjusts automatically
- Export includes all panels
Story Points
8 points