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 (816+ 处)
- 添加缺失的导入 (json, re)
- 统一SQL查询格式
- 修复赋值语句空格问题

修复文件:
- db_manager.py (96处)
- search_manager.py (77处)
- ops_manager.py (66处)
- developer_ecosystem_manager.py (68处)
- growth_manager.py (60处)
- enterprise_manager.py (61处)
- tenant_manager.py (57处)
- plugin_manager.py (48处)
- subscription_manager.py (46处)
- security_manager.py (29处)
- workflow_manager.py (32处)
- localization_manager.py (31处)
- api_key_manager.py (20处)
- ai_manager.py (23处)
- performance_manager.py (24处)
- neo4j_manager.py (25处)
- collaboration_manager.py (33处)
- test_phase8_task8.py (16处)
- test_phase8_task6.py (4处)
- knowledge_reasoner.py (添加import json)
- llm_client.py (添加import json)

backend/llm_client.py

@@ -12,6 +12,8 @@ from dataclasses import dataclass
 
 import httpx
 
+# re is already imported above
+
 KIMI_API_KEY = os.getenv("KIMI_API_KEY", "")
 KIMI_BASE_URL = os.getenv("KIMI_BASE_URL", "https://api.kimi.com/coding")