feat(core+health): HealthDataProvider 扩展趋势分析预计算数据

- erp-core: 新增 get_trend_analysis_data() trait 方法和配套 DTO
  (TrendAnalysisDto, MetricTrendAnalysis, RegressionStats, AnomalyInfo)
- erp-health: 实现 get_trend_analysis_data()，查询 vital_signs 时间序列
  后调用 trend_stats 模块计算线性回归和异常检测，返回结构化统计摘要

crates/erp-core/src/health_provider.rs

@@ -37,6 +37,15 @@ pub trait HealthDataProvider: Send + Sync {
         tenant_id: Uuid,
         report_id: Uuid,
     ) -> AppResult<HealthReportDto>;
+
+    /// 获取趋势分析预计算数据（统计摘要 + 异常检测）
+    async fn get_trend_analysis_data(
+        &self,
+        tenant_id: Uuid,
+        patient_id: Uuid,
+        metrics: &[String],
+        range: &TimeRange,
+    ) -> AppResult<TrendAnalysisDto>;
 }
 
 // === DTO 定义 ===
@@ -97,3 +106,56 @@ pub struct ReportSectionDto {
     pub findings: Vec<String>,
     pub abnormal_items: Vec<String>,
 }
+
+// === 趋势分析 DTO ===
+
+/// 趋势方向
+#[derive(Debug, Clone, Serialize, Deserialize)]
+#[serde(rename_all = "lowercase")]
+pub enum TrendDirection {
+    Rising,
+    Falling,
+    Stable,
+}
+
+/// 趋势分析整体 DTO
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct TrendAnalysisDto {
+    pub patient_id: Uuid,
+    pub period_start: String,
+    pub period_end: String,
+    pub metrics: Vec<MetricTrendAnalysis>,
+}
+
+/// 单个指标的趋势分析结果
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct MetricTrendAnalysis {
+    pub metric: String,
+    pub unit: String,
+    pub data_point_count: usize,
+    /// 线性回归统计（数据不足时为 None）
+    pub regression: Option<RegressionStats>,
+    /// 检测到的异常点
+    pub anomalies: Vec<AnomalyInfo>,
+}
+
+/// 线性回归统计摘要
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct RegressionStats {
+    pub slope: f64,
+    pub intercept: f64,
+    pub r_squared: f64,
+    pub direction: TrendDirection,
+    pub daily_change: f64,
+    pub period_change: f64,
+}
+
+/// 异常点信息
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct AnomalyInfo {
+    pub date: String,
+    pub value: f64,
+    pub mean: f64,
+    pub std_dev: f64,
+    pub deviation: f64,
+}