fix: auto-fix code issues (cron)

- 修复隐式 Optional 类型注解 (RUF013)
- 修复不必要的赋值后返回 (RET504)
- 优化列表推导式 (PERF401)
- 修复未使用的参数 (ARG002)
- 清理重复导入
- 优化异常处理

backend/security_manager.py

@@ -464,7 +464,9 @@ class SecurityManager:
         return logs
 
     def get_audit_stats(
-        self, start_time: str | None = None, end_time: str | None = None,
+        self,
+        start_time: str | None = None,
+        end_time: str | None = None,
     ) -> dict[str, Any]:
         """获取审计统计"""
         conn = sqlite3.connect(self.db_path)
@@ -882,7 +884,10 @@ class SecurityManager:
         return success
 
     def apply_masking(
-        self, text: str, project_id: str, rule_types: list[MaskingRuleType] | None = None,
+        self,
+        text: str,
+        project_id: str,
+        rule_types: list[MaskingRuleType] | None = None,
     ) -> str:
         """应用脱敏规则到文本"""
         rules = self.get_masking_rules(project_id)
@@ -906,7 +911,9 @@ class SecurityManager:
         return masked_text
 
     def apply_masking_to_entity(
-        self, entity_data: dict[str, Any], project_id: str,
+        self,
+        entity_data: dict[str, Any],
+        project_id: str,
     ) -> dict[str, Any]:
         """对实体数据应用脱敏"""
         masked_data = entity_data.copy()
@@ -982,7 +989,9 @@ class SecurityManager:
         return policy
 
     def get_access_policies(
-        self, project_id: str, active_only: bool = True,
+        self,
+        project_id: str,
+        active_only: bool = True,
     ) -> list[DataAccessPolicy]:
         """获取数据访问策略"""
         conn = sqlite3.connect(self.db_path)
@@ -1021,14 +1030,18 @@ class SecurityManager:
         return policies
 
     def check_access_permission(
-        self, policy_id: str, user_id: str, user_ip: str | None = None,
+        self,
+        policy_id: str,
+        user_id: str,
+        user_ip: str | None = None,
     ) -> tuple[bool, str | None]:
         """检查访问权限"""
         conn = sqlite3.connect(self.db_path)
         cursor = conn.cursor()
 
         cursor.execute(
-            "SELECT * FROM data_access_policies WHERE id = ? AND is_active = 1", (policy_id,),
+            "SELECT * FROM data_access_policies WHERE id = ? AND is_active = 1",
+            (policy_id,),
         )
         row = cursor.fetchone()
         conn.close()
@@ -1163,7 +1176,10 @@ class SecurityManager:
         return request
 
     def approve_access_request(
-        self, request_id: str, approved_by: str, expires_hours: int = 24,
+        self,
+        request_id: str,
+        approved_by: str,
+        expires_hours: int = 24,
     ) -> AccessRequest | None:
         """批准访问请求"""
         conn = sqlite3.connect(self.db_path)