feat(aiot): 告警结束接口 + 持续时长更新 + first_frame_time存储

新增告警结束接口：
- 新增EdgeAlarmResolve请求模型
- 新增POST /edge/resolve端点（无需认证，Edge设备调用）
- 新增resolve_alarm服务方法：更新duration_ms、last_frame_time
- 人员回岗/非工作时间自动设置alarm_status=CLOSED、handle_status=DONE

告警创建修复：
- create_from_edge_report现在从ext_data读取first_frame_time写入数据库
- create_from_edge_report现在从ext_data读取duration_ms写入数据库
- 统一edge_node_id从ext_data提取

app/services/alarm_event_service.py

@@ -171,12 +171,21 @@ class AlarmEventService:
 
             alarm_type = data.get("alarm_type", "unknown")
             alarm_level = data.get("alarm_level")
+            ext_data = data.get("ext_data") or {}
             if alarm_level is None:
                 # 从 ext_data 取 duration_ms
-                ext_data = data.get("ext_data") or {}
                 duration_ms = ext_data.get("duration_ms")
                 alarm_level = _determine_alarm_level(alarm_type, confidence or 0, duration_ms)
 
+            # 解析 first_frame_time（离岗开始时间，由 Edge 在 ext_data 中传递）
+            first_frame_time = None
+            first_frame_time_str = ext_data.get("first_frame_time")
+            if first_frame_time_str:
+                try:
+                    first_frame_time = datetime.fromisoformat(first_frame_time_str.replace("Z", "+00:00"))
+                except ValueError:
+                    first_frame_time = None
+
             alarm = AlarmEvent(
                 alarm_id=alarm_id,
                 alarm_type=alarm_type,
@@ -184,12 +193,14 @@ class AlarmEventService:
                 device_id=data.get("device_id", "unknown"),
                 scene_id=data.get("scene_id"),
                 event_time=event_time,
+                first_frame_time=first_frame_time,
+                duration_ms=ext_data.get("duration_ms"),
                 alarm_level=alarm_level,
                 confidence_score=confidence,
                 alarm_status="NEW",
                 handle_status="UNHANDLED",
-                snapshot_url=data.get("snapshot_url"),  # COS object_key
-                edge_node_id=data.get("ext_data", {}).get("edge_node_id") if data.get("ext_data") else None,
+                snapshot_url=data.get("snapshot_url"),
+                edge_node_id=ext_data.get("edge_node_id"),
             )
 
             db.add(alarm)
@@ -520,6 +531,46 @@ class AlarmEventService:
         finally:
             db.close()
 
+    def resolve_alarm(self, alarm_id: str, duration_ms: int, last_frame_time: str, resolve_type: str) -> bool:
+        """更新告警的持续时长和结束时间"""
+        db = get_session()
+        try:
+            alarm = db.query(AlarmEvent).filter(AlarmEvent.alarm_id == alarm_id).first()
+            if not alarm:
+                return False
+
+            alarm.duration_ms = duration_ms
+
+            # 解析 last_frame_time
+            try:
+                alarm.last_frame_time = datetime.fromisoformat(last_frame_time.replace("Z", "+00:00"))
+            except Exception:
+                alarm.last_frame_time = datetime.now(timezone.utc)
+
+            # 如果是人员回岗，标记为自动关闭
+            if resolve_type == "person_returned":
+                alarm.alarm_status = "CLOSED"
+                alarm.handle_status = "DONE"
+                alarm.handle_remark = "人员回岗自动关闭"
+                alarm.handled_at = datetime.now(timezone.utc)
+            elif resolve_type == "non_work_time":
+                alarm.alarm_status = "CLOSED"
+                alarm.handle_status = "DONE"
+                alarm.handle_remark = "非工作时间自动关闭"
+                alarm.handled_at = datetime.now(timezone.utc)
+
+            alarm.updated_at = datetime.now(timezone.utc)
+            db.commit()
+
+            logger.info(f"告警已更新结束信息: {alarm_id}, duration={duration_ms}ms, type={resolve_type}")
+            return True
+        except Exception as e:
+            db.rollback()
+            logger.error(f"更新告警结束信息失败: {e}")
+            return False
+        finally:
+            db.close()
+
     def save_llm_analysis(
         self,
         alarm_id: str,