[Remotion] Calendar composition

## Summary
Create Remotion composition showing unified calendar.

## Scene
- Calendar view (week or month)
- Events from multiple sources
- Visual distinction between sources
- Possible navigation animation

## Duration
10-15 seconds loop

## Acceptance Criteria
- [ ] Calendar UI clear
- [ ] Multi-source aggregation visible
- [ ] Smooth transitions
- [ ] Works in dark/light themes