feat(timeline): merge bp.systolic + bp.diastolic into single entry

- TimelineEntry.from(indicators:) 批处理:找 bp.systolic 配对同 capturedAt
  (±5s)的 bp.diastolic,合并成 '血压 120/80 mmHg' 一行
- 未配对的 systolic 单独退回 from(indicator:)
- 非 bp.* series 不动
- ArchiveListView + HomeView 改用 from(indicators:) 批处理
- 6 个新测试覆盖配对/未配对/异常标记/非 bp 不动/不同时间不合并

康康/Features/Home/HomeView.swift

@@ -19,7 +19,7 @@ struct HomeView: View {
     @MainActor
     private var recentEntries: [TimelineEntry] {
         let all =
-            indicators.map(TimelineEntry.from(indicator:)) +
+            TimelineEntry.from(indicators: indicators) +
             reports.map(TimelineEntry.from(report:)) +
             diaries.map(TimelineEntry.from(diary:)) +
             symptoms.map(TimelineEntry.from(symptom:))