feat: Comparison history/library #36
Description
Summary
Save and browse previous comparisons for reuse.
Motivation
Users often create similar comparisons - history allows quick access.
Implementation
- Save comparisons with metadata
- Browse history in side panel
- Load previous comparison
- Delete from history
Technical Considerations
- Local storage (CoreData or JSON files)
- Thumbnail generation for previews
- Search/filter by title or date
Acceptance Criteria
- Auto-save comparisons
- History panel with thumbnails
- Load comparison from history
- Delete individual items
Story Points
5 points