fix(heartbeat): 對齊整點發送避免多replica各自發 + KM向量化改查embedding欄位

- _heartbeat_loop: 先 sleep 到下一個整點倍數再開始循環
  避免 3 個 replica 啟動時間不同導致短時間內收到多條心跳
- heartbeat_report_service: km_vectorized 改查 KnowledgeEntryRecord.embedding IS NOT NULL
  原本錯誤查 IncidentRecord.vectorized 導致顯示 0/714 (0%)

2026-04-12 ogt (ADR-073 heartbeat fix)

apps/api/src/services/heartbeat_report_service.py

@@ -339,15 +339,13 @@ class HeartbeatReportService:
                 km_total = await db.scalar(select(func.count()).select_from(KnowledgeEntryRecord))
                 stats.km_total = km_total or 0
 
-                # Incident 向量化數
+                # KM 向量化數（embedding IS NOT NULL）
+                # 注意：knowledge_entries 無 vectorized 欄位，用 embedding 判斷
                 vec_count = await db.scalar(
-                    select(func.count()).select_from(IncidentRecord)
-                    .where(IncidentRecord.vectorized == True)  # noqa: E712
+                    select(func.count()).select_from(KnowledgeEntryRecord)
+                    .where(KnowledgeEntryRecord.embedding.isnot(None))
                 )
-                inc_total = await db.scalar(select(func.count()).select_from(IncidentRecord))
                 stats.km_vectorized = vec_count or 0
-                if not stats.km_total:
-                    stats.km_total = inc_total or 0
 
                 # 24h 修復統計
                 since = datetime.utcnow() - timedelta(hours=24)

apps/api/src/services/telegram_gateway.py

@@ -4748,6 +4748,16 @@ class TelegramGateway:
         """
         interval_seconds = interval_minutes * 60
 
+        # 對齊到下一個整點倍數（例如 interval=30 → 對齊到 :00 或 :30）
+        # 避免多 replica 因啟動時間不同而各自發送
+        now_ts = datetime.now(UTC).timestamp()
+        next_slot = (int(now_ts / interval_seconds) + 1) * interval_seconds
+        wait_seconds = next_slot - now_ts
+        try:
+            await asyncio.sleep(wait_seconds)
+        except asyncio.CancelledError:
+            return
+
         while self._heartbeat_active:
             try:
                 await self.send_heartbeat()