/// Adherence statistics calculated for a medication
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AdherenceStats {
    pub medication_id: String,
    pub total_doses: i64,
    pub scheduled_doses: i64,
    pub taken_doses: i64,
    pub missed_doses: i64,
    pub adherence_rate: f64,
    pub period_days: i64,
}