feat: extend equipment and workout models with service tracking

internal/workout/repository.go

@@ -62,4 +62,23 @@ func (r *Repository) UpdateWorkout(workout *Workout) error {
 func (r *Repository) DeleteWorkout(id, userID uint) error {
 	return database.DB.Where("id = ? AND user_id = ?", id, userID).
 		Delete(&Workout{}).Error
+}
+
+type EquipmentStat struct {
+	EquipmentID   uint    `json:"equipment_id"`
+	TotalRides    int     `json:"total_rides"`
+	TotalDistance  float64 `json:"total_distance"`
+	TotalDuration int     `json:"total_duration"`
+}
+
+func (r *Repository) GetEquipmentStats(userID uint) ([]EquipmentStat, error) {
+	var stats []EquipmentStat
+	if err := database.DB.Model(&Workout{}).
+		Select("equipment_id, COUNT(*) as total_rides, COALESCE(SUM(distance), 0) as total_distance, COALESCE(SUM(duration), 0) as total_duration").
+		Where("user_id = ? AND equipment_id IS NOT NULL", userID).
+		Group("equipment_id").
+		Scan(&stats).Error; err != nil {
+		return nil, err
+	}
+	return stats, nil
 }