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/test_phase7_task6_8.py

@@ -4,19 +4,19 @@ InsightFlow Phase 7 Task 6 & 8 测试脚本
 测试高级搜索与发现、性能优化与扩展功能
 """
 
-from performance_manager import (
-    get_performance_manager, CacheManager,
-    TaskQueue, PerformanceMonitor
-)
-from search_manager import (
-    get_search_manager, FullTextSearch,
-    SemanticSearch, EntityPathDiscovery,
-    KnowledgeGapDetection
-)
 import os
 import sys
 import time
 
+from performance_manager import CacheManager, PerformanceMonitor, TaskQueue, get_performance_manager
+from search_manager import (
+    EntityPathDiscovery,
+    FullTextSearch,
+    KnowledgeGapDetection,
+    SemanticSearch,
+    get_search_manager,
+)
+
 # 添加 backend 到路径
 sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))