fix(health): align WorkoutSummary keys with Android and remove duplicate iOS properties

[marcos-abreu]

Summary

This PR fixes a mismatch between the keys returned by the native Android implementation and those expected by the Dart layer when creating a WorkoutSummary.

Problem

• The Android layer returns workout properties in camelCase (totalDistance, totalEnergyBurned, etc.).
• The Dart layer was expecting snake_case (total_distance, total_energy_burned, etc.).
• The iOS layer returned both camelCase and snake_case.

This mismatch caused WorkoutSummary values to be unavailable when reading workouts from Android.

Changes

• Updated Dart’s WorkoutSummary.fromHealthDataPoint and related checks to use camelCase keys (matching Android and also iOS).
• Removed the duplicate snake_case properties from iOS (workout_type, total_distance, total_energy_burned).
• Ensured consistency between Android, iOS, and Dart layers.

Impact

• Fixes WorkoutSummary parsing for Android.
• Cleans up unused keys from iOS without changing Dart’s expectations.
• No breaking change for public Dart API (users continue to consume WorkoutSummary the same way).