Apple fitness — author with WorkoutKit, track with HealthKit

Build fitness/workout features on Apple platforms — WorkoutKit to author, preview, and schedule structured workouts (custom workouts, interval blocks, goals, and heart-rate/pace/power/cadence alerts) to Apple Watch, and HealthKit's live workout session on watchOS (HKWorkoutSession + HKLiveWorkoutBuilder) to track and save an HKWorkout with route data. Covers the split between authoring plans (WorkoutKit, iOS+watch) and live tracking (HealthKit, watch), workout activity types, and saving/reading workouts. Pairs with the healthkit skill for the underlying store. Use when composing a training plan, scheduling a workout to the Watch, tracking a live workout, or reading past w…