Live activity view during workouts.

Bug fixes, additional exercises, and circuits!
- New feature: add exercises to your workout in progress.
- Additional Exercises—now 200!
- Circuits make it easy to cycle through a subset of exercises in your workout.
- Workouts now correctly only display the plate visualizer for workouts with barbells.
- Bodyweight Exercises now include a total rep counter.
- Nutrition macros can now be adjusted by dragging the number.