fix(flywheel): 自動修復後移除 Telegram 按鈕 + 心跳告警排除飛輪

問題: 自動修復成功後 Telegram 卡片仍顯示批准/拒絕/靜默按鈕

Fix 1 — Telegram 卡片回饋閉環 (積木化合規):
- telegram_gateway.send_approval_card: 發送後自動存 tg_approval:{id} 到 Redis
- telegram_gateway.mark_auto_repaired(): 新方法 — 移除按鈕 + reply 結果
- _try_auto_repair_background: 改呼叫 gateway.mark_auto_repaired() (Service 層)

Fix 2 — 心跳/看門狗告警排除飛輪:
- constants.py: is_heartbeat_alertname() + HEARTBEAT_ALERT_NAMES
- NoAlertsReceived2Hours 等不觸發 _try_auto_repair_background

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/api/src/core/constants.py

@@ -85,6 +85,34 @@ CICD_ALERT_SUFFIXES = (
 # CI/CD 告警關鍵字 (不區分大小寫)
 CICD_ALERT_KEYWORDS = ("CI/CD", "cicd")
 
+# =============================================================================
+# Heartbeat/Watchdog Alert Detection (2026-04-10 Claude Sonnet 4.6 Asia/Taipei)
+# 心跳/看門狗告警不觸發自動修復飛輪 — 這類告警代表監控系統狀態，不是服務故障
+# =============================================================================
+HEARTBEAT_ALERT_NAMES = frozenset({
+    "Watchdog",
+    "DeadMansSwitch",
+    "NoAlertsReceived",
+    "NoAlertsReceived2Hours",
+    "AlertmanagerDown",
+    "PrometheusNotConnectedToAlertmanager",
+})
+
+HEARTBEAT_ALERT_KEYWORDS = ("NoAlertsReceived", "Watchdog", "DeadMansSwitch", "Heartbeat")
+
+
+def is_heartbeat_alertname(alertname: str) -> bool:
+    """
+    判斷 alertname 是否為心跳/看門狗告警
+
+    心跳告警代表監控系統自身健康狀態，不是服務故障，
+    不應進入自動修復飛輪（不存在對應的 Playbook 修復動作）。
+    """
+    return (
+        alertname in HEARTBEAT_ALERT_NAMES
+        or any(kw in alertname for kw in HEARTBEAT_ALERT_KEYWORDS)
+    )
+
 
 def is_cicd_alertname(alertname: str) -> bool:
     """