fix(adr075): 修補斷點E — _push_to_telegram_background 補 TYPE-8M routing

斷點E：alertmanager webhook 走 _push_to_telegram_background，
未含 TYPE-8M branch，導致 meta alert 從未送出。

- webhooks.py: 新增 alert_category 參數 + TYPE-8M branch
- incident_service.py: 還原 rule 5 僅攔 watchdog/heartbeat，
  移除誤加的 backup startswith 規則（VeleroBackup 由 K8s rule 接管）

Tests: 52/52 passed

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

apps/api/src/api/v1/webhooks.py

@@ -307,6 +307,8 @@ async def _push_to_telegram_background(
     # ADR-073 Fix: 傳入 notification_type 以正確路由 TYPE-4D Config Drift 卡片
     notification_type: str = "",
     diff_summary: str = "",
+    # 2026-04-12 ogt: ADR-075 斷點 E 修復 — alert_category 傳入以啟用 TYPE-8M 路由
+    alert_category: str = "",
 ) -> None:
     """
     背景任務: 推送待簽核卡片到 Telegram (v7.0 含 SignOz 整合)
@@ -344,6 +346,26 @@ async def _push_to_telegram_background(
             )
             return
 
+        # 2026-04-12 ogt: ADR-075 斷點 E 修復 — TYPE-8M Meta-System 使用專屬卡片
+        # alertchain_health / flywheel_health → ⚙️ META SYSTEM 卡片，不發群組
+        if notification_type == "TYPE-8M" or alert_category in ("alertchain_health", "flywheel_health"):
+            await gateway.send_meta_alert(
+                incident_id=incident_id,
+                approval_id=approval_id,
+                alertname=resource_name,
+                alert_category=alert_category,
+                diagnosis=root_cause[:100],
+                severity_level=risk_level,
+                system_impact=root_cause[:150],
+            )
+            logger.info(
+                "telegram_push_success_type8m",
+                approval_id=approval_id,
+                incident_id=incident_id,
+                alert_category=alert_category,
+            )
+            return
+
         # 如果是收斂告警，在訊息中加入聚合次數
         root_cause_with_count = root_cause
         if hit_count > 1:
@@ -1463,6 +1485,8 @@ async def alertmanager_webhook(
                 incident_id=incident_id,
                 # ADR-073: 路由 TYPE-4D → send_drift_card
                 notification_type=notification_type,
+                # ADR-075 斷點 E 修復: 路由 TYPE-8M → send_meta_alert
+                alert_category=alert_category,
             )
 
             record_alert_chain_success("alertmanager")
@@ -1530,6 +1554,8 @@ async def alertmanager_webhook(
                 incident_id=fallback_incident_id,
                 # ADR-073: 路由 TYPE-4D → send_drift_card
                 notification_type=notification_type,
+                # ADR-075 斷點 E 修復: 路由 TYPE-8M → send_meta_alert
+                alert_category=alert_category,
             )
 
             return AlertResponse(

apps/api/src/services/incident_service.py

@@ -164,14 +164,8 @@ def classify_alert_early(alertname: str, severity: str, labels: dict | None = No
         return "info", "TYPE-1"
 
     # 5. Backup / Heartbeat — 純資訊，不進 LLM
-    # HostBackupFailed 必須在 Host prefix 前攔截，否則被歸 host_resource/TYPE-3
-    # 2026-04-12 ogt: 補充 HostBackup/Backup/VeleroBackup 前綴
-    if (
-        "watchdog" in alertname_lower
-        or alertname == "Heartbeat"
-        or alertname.startswith(("HostBackup", "Backup", "VeleroBackup", "BackupRestore"))
-        or "backup" in alertname_lower
-    ):
+    # VeleroBackup 由 K8s prefix 規則接管，此處只攔 watchdog/heartbeat
+    if "watchdog" in alertname_lower or alertname == "Heartbeat":
         return "backup", "TYPE-1"
 
     # 6. 主機資源（從 infrastructure 分離，ADR-075 統帥決議）