功能：area_id 存储 + 工单对接代码完善 + 心跳端点

- AlarmEvent 模型添加 area_id 字段
- create_from_edge_report 提取 ext_data.area_id 存储
- 心跳端点 POST /api/ai/device/heartbeat
- work_order_client: create_order 支持完整参数（description/priority/triggerSource/cameraId/imageUrl）
- notify_dispatch: 工单标题中文化、alarmType 中文映射、永久 COS URL、triggerSource 来源判断
- oss_storage: 新增 get_permanent_url 方法
- 工单创建测试脚本

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/models.py

@@ -271,13 +271,14 @@ class AlarmEvent(Base):
     first_frame_time = Column(DateTime, comment="首帧时间")
     last_frame_time = Column(DateTime, comment="末帧时间")
     duration_ms = Column(Integer, comment="持续时长(毫秒)")
-    alarm_level = Column(SmallInteger, comment="告警级别: 1提醒 2一般 3严重 4紧急")
+    alarm_level = Column(SmallInteger, comment="告警级别: 0紧急 1重要 2普通 3轻微")
     confidence_score = Column(Float, comment="置信度 0-1")
     alarm_status = Column(String(20), default="NEW", comment="告警状态: NEW/CONFIRMED/FALSE/CLOSED")
     handle_status = Column(String(20), default="UNHANDLED", comment="处理状态: UNHANDLED/HANDLING/DONE")
     snapshot_url = Column(String(512), comment="截图URL")
     video_url = Column(String(512), comment="视频URL")
     edge_node_id = Column(String(64), comment="边缘节点ID")
+    area_id = Column(BigInteger, comment="所属区域ID")
     handler = Column(String(64), comment="处理人")
     handle_remark = Column(Text, comment="处理备注")
     handled_at = Column(DateTime, comment="处理时间")
@@ -308,6 +309,7 @@ class AlarmEvent(Base):
             "snapshot_url": self.snapshot_url,
             "video_url": self.video_url,
             "edge_node_id": self.edge_node_id,
+            "area_id": self.area_id,
             "handler": self.handler,
             "handle_remark": self.handle_remark,
             "handled_at": self.handled_at.strftime('%Y-%m-%d %H:%M:%S') if self.handled_at else None,