fix(flywheel): P2 Approval 逾期不結案 → KM 學習鏈斷鏈修復

問題根因：
  PENDING approval 無人處置超過 48h 後應自動 EXPIRED，
  但 get_pending_approvals() 只在用戶開 UI 時觸發，
  若無人開 UI → Incident 永遠 PENDING → KM 永遠不寫入
  → Phase 6 SLO human_override_rate 低估，EWMA 缺少負向樣本。

修復：
  1. anomaly_counter.py: 新增 "timeout_ignored" disposition 類型，
     與 auto_repair / human_approved / manual_resolved 區分
  2. incident_service.py: resolve_incident() 新增 resolution_type 參數，
     resolution_type="timeout" 時記錄 "timeout_ignored" 而非 "manual_resolved"
  3. jobs/approval_timeout_resolver.py (新): 每小時掃描逾期 PENDING approval，
     批次標記 EXPIRED，對每筆有 incident_id 的記錄呼叫 resolve_incident("timeout")
  4. main.py: startup 掛載 approval_timeout_resolver 排程（interval=3600s）

效果：
  - 告警無人處置 48h → Incident 自動結案 → KM 寫入 → EWMA 取得樣本
  - disposition="timeout_ignored" 讓 SLO 計算正確區分「AI 建議被忽略」
  - 飛輪學習鏈對「無人處置告警」閉環

2026-04-15 ogt + Claude Sonnet 4.6（亞太）

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

apps/api/src/services/anomaly_counter.py

@@ -387,7 +387,7 @@ class AnomalyCounter:
     # 2026-04-07 Claude Code: Sprint 4 A2/A3 — 處置類型統計
     # ==========================================================================
 
-    VALID_DISPOSITION_TYPES = {"auto_repair", "human_approved", "manual_resolved", "cold_start_trust"}
+    VALID_DISPOSITION_TYPES = {"auto_repair", "human_approved", "manual_resolved", "cold_start_trust", "timeout_ignored"}
 
     async def record_disposition(
         self,

apps/api/src/services/incident_service.py

@@ -915,7 +915,11 @@ class IncidentService:
 
         return incident
 
-    async def resolve_incident(self, incident_id: str) -> Incident | None:
+    async def resolve_incident(
+        self,
+        incident_id: str,
+        resolution_type: str = "manual",
+    ) -> Incident | None:
         """
         將 Incident 狀態更新為 RESOLVED
 
@@ -923,6 +927,12 @@ class IncidentService:
 
         Args:
             incident_id: 事件 ID
+            resolution_type: "manual"（預設）| "timeout"（Approval 48h 逾期自動結案）
+
+        ADR-073 補丁 2026-04-15 ogt + Claude Sonnet 4.6:
+          新增 resolution_type="timeout" 路徑 — Approval EXPIRED 時由
+          approval_timeout_resolver 呼叫，記錄 "timeout_ignored" disposition
+          而非 "manual_resolved"，確保 EWMA 採樣正確區分人工結案與逾期拋棄。
 
         Returns:
             Incident | None: 更新後的事件，失敗返回 None
@@ -998,7 +1008,8 @@ class IncidentService:
                     or disposition["cold_start_trust"] > 0
                 )
                 if not has_system_resolution:
-                    await counter.record_disposition(anomaly_key, "manual_resolved")
+                    disp = "timeout_ignored" if resolution_type == "timeout" else "manual_resolved"
+                    await counter.record_disposition(anomaly_key, disp)
         except Exception as _disp_e:
             logger.warning("disposition_manual_resolve_failed", error=str(_disp_e))