fix: auto-fix code issues (cron)

- 修复重复导入/字段
- 修复异常处理
- 修复PEP8格式问题
- 添加类型注解

backend/ops_manager.py

@@ -456,13 +456,13 @@ class OpsManager:
         self._evaluator_thread = None
         self._register_default_evaluators()
 
-    def _get_db(self):
+    def _get_db(self) -> None:
         """获取数据库连接"""
         conn = sqlite3.connect(self.db_path)
         conn.row_factory = sqlite3.Row
         return conn
 
-    def _register_default_evaluators(self):
+    def _register_default_evaluators(self) -> None:
         """注册默认的告警评估器"""
         self._alert_evaluators[AlertRuleType.THRESHOLD.value] = self._evaluate_threshold_rule
         self._alert_evaluators[AlertRuleType.ANOMALY.value] = self._evaluate_anomaly_rule
@@ -1249,7 +1249,7 @@ class OpsManager:
 
         return self.get_alert(alert_id)
 
-    def _increment_suppression_count(self, alert_id: str):
+    def _increment_suppression_count(self, alert_id: str) -> None:
         """增加告警抑制计数"""
         with self._get_db() as conn:
             conn.execute(
@@ -1262,7 +1262,7 @@ class OpsManager:
             )
             conn.commit()
 
-    def _update_alert_notification_status(self, alert_id: str, channel_id: str, success: bool):
+    def _update_alert_notification_status(self, alert_id: str, channel_id: str, success: bool) -> None:
         """更新告警通知状态"""
         with self._get_db() as conn:
             row = conn.execute("SELECT notification_sent FROM alerts WHERE id = ?", (alert_id,)).fetchone()
@@ -1276,7 +1276,7 @@ class OpsManager:
                 )
                 conn.commit()
 
-    def _update_channel_stats(self, channel_id: str, success: bool):
+    def _update_channel_stats(self, channel_id: str, success: bool) -> None:
         """更新渠道统计"""
         now = datetime.now().isoformat()
 
@@ -1769,9 +1769,7 @@ class OpsManager:
                 return self._row_to_scaling_event(row)
             return None
 
-    def update_scaling_event_status(
-        self, event_id: str, status: str, error_message: str = None
-    ) -> ScalingEvent | None:
+    def update_scaling_event_status(self, event_id: str, status: str, error_message: str = None) -> ScalingEvent | None:
         """更新扩缩容事件状态"""
         now = datetime.now().isoformat()
 
@@ -2339,7 +2337,7 @@ class OpsManager:
 
         return record
 
-    def _complete_backup(self, record_id: str, size_bytes: int, checksum: str = None):
+    def _complete_backup(self, record_id: str, size_bytes: int, checksum: str = None) -> None:
         """完成备份"""
         now = datetime.now().isoformat()
         checksum = checksum or hashlib.sha256(str(time.time()).encode()).hexdigest()[:16]