fix: alarm_event_service 时间统一为北京时间

- 所有 datetime.now(timezone.utc) 替换为 beijing_now()
- 保持与边缘端上报时间（北京时间）一致

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

app/services/alarm_event_service.py

@@ -11,11 +11,12 @@ from sqlalchemy import func
 from app.models import AlarmEvent, AlarmEventExt, AlarmLlmAnalysis, get_session
 from app.services.oss_storage import get_oss_storage
 from app.utils.logger import logger
+from app.utils.timezone import beijing_now
 
 
 def generate_alarm_id() -> str:
     """生成告警ID: ALM + YYYYMMDDHHmmss + 8位uuid"""
-    timestamp = datetime.now(timezone.utc).strftime("%Y%m%d%H%M%S")
+    timestamp = beijing_now().strftime("%Y%m%d%H%M%S")
     unique_id = uuid.uuid4().hex[:8].upper()
     return f"ALM{timestamp}{unique_id}"
 
@@ -64,9 +65,9 @@ class AlarmEventService:
                 try:
                     event_time = datetime.fromisoformat(timestamp_str.replace("Z", "+00:00"))
                 except ValueError:
-                    event_time = datetime.now(timezone.utc)
+                    event_time = beijing_now()
             else:
-                event_time = datetime.now(timezone.utc)
+                event_time = beijing_now()
 
             # 解析 first_frame_time（告警首次触发时间）
             first_frame_str = mqtt_data.get("first_frame_time")
@@ -169,9 +170,9 @@ class AlarmEventService:
                 try:
                     event_time = datetime.fromisoformat(event_time_str.replace("Z", "+00:00"))
                 except ValueError:
-                    event_time = datetime.now(timezone.utc)
+                    event_time = beijing_now()
             else:
-                event_time = datetime.now(timezone.utc)
+                event_time = beijing_now()
 
             # 置信度
             confidence = data.get("confidence_score")
@@ -251,11 +252,11 @@ class AlarmEventService:
                 try:
                     event_time = datetime.fromisoformat(trigger_time.replace("Z", "+00:00"))
                 except ValueError:
-                    event_time = datetime.now(timezone.utc)
+                    event_time = beijing_now()
             elif isinstance(trigger_time, datetime):
                 event_time = trigger_time
             else:
-                event_time = datetime.now(timezone.utc)
+                event_time = beijing_now()
 
             confidence = data.get("confidence")
             if confidence is not None:
@@ -414,8 +415,8 @@ class AlarmEventService:
                 alarm.handle_remark = remark
             if handler:
                 alarm.handler = handler
-            alarm.handled_at = datetime.now(timezone.utc)
+            alarm.handled_at = beijing_now()
-            alarm.updated_at = datetime.now(timezone.utc)
+            alarm.updated_at = beijing_now()
 
             db.commit()
             db.refresh(alarm)
@@ -557,26 +558,26 @@ class AlarmEventService:
                 parsed_time = datetime.fromisoformat(last_frame_time.replace("Z", "+00:00"))
                 alarm.last_frame_time = parsed_time.replace(microsecond=0)
             except Exception:
-                alarm.last_frame_time = datetime.now(timezone.utc).replace(microsecond=0)
+                alarm.last_frame_time = beijing_now().replace(microsecond=0)
 
             # 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)
+                alarm.handled_at = beijing_now()
             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.handled_at = beijing_now()
             elif resolve_type == "intrusion_cleared":
                 alarm.alarm_status = "CLOSED"
                 alarm.handle_status = "DONE"
                 alarm.handle_remark = "入侵消失自动关闭（持续无人180秒）"
-                alarm.handled_at = datetime.now(timezone.utc)
+                alarm.handled_at = beijing_now()
 
-            alarm.updated_at = datetime.now(timezone.utc)
+            alarm.updated_at = beijing_now()
             db.commit()
 
             logger.info(f"告警已更新结束信息: {alarm_id}, duration={duration_ms}ms, type={resolve_type}")