feat(06-01): Implement workout swap/rotation system - API, DB, frontend
- Add workout_swaps table migration (007_add_workout_swap_tracking.sql)
- Implement 4 API endpoints: POST /swap, DELETE /undo, GET /swaps, GET /available
- Add request validation, error handling, user isolation, muscle group checks
- Create SwapWorkoutModal React component with modal UI
- Integrate swap functionality into WorkoutPage
- Add proper styling for swap modal
- All endpoints require authentication
- Database migration includes performance indexes
clawd
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