HKWorkoutSession(healthStore:configuration:) + associatedWorkoutBuilder +
HKLiveWorkoutDataSource. Collecte FC (mostRecent), calories/distance (sum) via
statistics(for:), publication @Published sur main, envoi throttlé (2s) vers
ConnectivityManager. Clôture async endCollection(at:)/finishWorkout(). Build OK.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>