feat: extend equipment and workout models with service tracking

internal/workout/service.go

@@ -85,4 +85,8 @@ func (s *Service) UpdateWorkoutWithMetrics(id, userID uint, distance float64, av
 
 func (s *Service) DeleteWorkout(id, userID uint) error {
 	return s.repo.DeleteWorkout(id, userID)
+}
+
+func (s *Service) GetEquipmentStats(userID uint) ([]EquipmentStat, error) {
+	return s.repo.GetEquipmentStats(userID)
 }