fix: auto-fix code issues (cron)

- 修复重复导入/字段 (llm_client.py 中的重复注释)
- 修复PEP8格式问题 (E501行长度超过100字符)
- 修复多行SQL语句和字符串格式化
- 修复f-string过长问题

涉及文件:
- backend/developer_ecosystem_manager.py
- backend/document_processor.py
- backend/enterprise_manager.py
- backend/export_manager.py
- backend/growth_manager.py
- backend/llm_client.py
- backend/localization_manager.py
- backend/main.py
- backend/neo4j_manager.py
- backend/ops_manager.py
- backend/performance_manager.py
- backend/plugin_manager.py
- backend/search_manager.py
- backend/security_manager.py
- backend/subscription_manager.py
- backend/tenant_manager.py
- backend/test_phase8_task6.py
- backend/test_phase8_task8.py
- backend/tingwu_client.py
- backend/workflow_manager.py

backend/workflow_manager.py

@@ -1019,20 +1019,23 @@ class WorkflowManager:
 
             # 成功次数
             success = conn.execute(
-                "SELECT COUNT(*) FROM workflow_logs WHERE workflow_id = ? AND status = 'success' AND created_at > ?",
+                """SELECT COUNT(*) FROM workflow_logs
+                WHERE workflow_id = ? AND status = 'success' AND created_at > ?""",
                 (workflow_id, since),
             ).fetchone()[0]
 
             # 失败次数
             failed = conn.execute(
-                "SELECT COUNT(*) FROM workflow_logs WHERE workflow_id = ? AND status = 'failed' AND created_at > ?",
+                """SELECT COUNT(*) FROM workflow_logs
+                WHERE workflow_id = ? AND status = 'failed' AND created_at > ?""",
                 (workflow_id, since),
             ).fetchone()[0]
 
             # 平均执行时间
             avg_duration = (
                 conn.execute(
-                    "SELECT AVG(duration_ms) FROM workflow_logs WHERE workflow_id = ? AND created_at > ?",
+                    """SELECT AVG(duration_ms) FROM workflow_logs
+                    WHERE workflow_id = ? AND created_at > ?""",
                     (workflow_id, since),
                 ).fetchone()[0]
                 or 0