feat: 传递离岗时长到告警记录

- ResultReporter AlertInfo 添加 duration_minutes
- main.py 使用 report_alert 替代 report_detection_alert
- _store_alert 保存 duration_minutes

core/result_reporter.py

@@ -37,6 +37,7 @@ class AlertInfo:
     message: Optional[str] = None
     screenshot: Optional[np.ndarray] = None
     timestamp: datetime = field(default_factory=datetime.now)
+    duration_minutes: Optional[float] = None
     
     def to_dict(self) -> Dict[str, Any]:
         """转换为字典"""
@@ -50,6 +51,7 @@ class AlertInfo:
             "bbox": self.bbox,
             "message": self.message,
             "timestamp": self.timestamp.isoformat(),
+            "duration_minutes": self.duration_minutes,
         }
 
 
@@ -211,6 +213,7 @@ class ResultReporter:
             image_path=image_path,
             status="pending",
             created_at=alert.timestamp,
+            duration_minutes=alert.duration_minutes,
         )
         
         if self._db_manager: