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
- 修复main.py中的语法错误（缺失try语句的from导入）
- 添加缺失的timedelta导入到plugin_manager.py
- 添加缺失的urllib.parse导入到plugin_manager.py和workflow_manager.py
- 添加缺失的os导入到document_processor.py
- 修复import排序问题
- 修复行长度超过100字符的问题
- 添加缺失的Alert导入到test_phase8_task8.py
- 添加缺失的get_export_manager导入到main.py

backend/knowledge_reasoner.py

@@ -340,7 +340,9 @@ class KnowledgeReasoner:
   "answer": "关联分析结果",
   "direct_connections": ["直接关联1"],
   "indirect_connections": ["间接关联1"],
-  "inferred_relations": [{{"source": "A", "target": "B", "relation": "可能关系", "confidence": 0.7}}],
+  "inferred_relations": [
+    {{"source": "A", "target": "B", "relation": "可能关系", "confidence": 0.7}}
+  ],
   "confidence": 0.85,
   "evidence": ["证据1"],
   "knowledge_gaps": []