refactor: 完成数据库重构 - 批量更新导入路径

- 更新35个文件的导入路径 (共65处修改)
- sqlalchemy_models  core.models (模型类)
- sqlalchemy_database_api  compatibility (兼容函数)
- database.database  core (初始化/关闭函数)
- 添加自动化导入更新工具 (scripts/update_database_imports.py)
- 所有兼容性层测试通过 (26/26)
- 数据库核心功能测试通过 (18/21)

src/chat/utils/statistic.py

@@ -3,8 +3,8 @@ from collections import defaultdict
 from datetime import datetime, timedelta
 from typing import Any
 
-from src.common.database.sqlalchemy_database_api import db_get, db_query, db_save
-from src.common.database.sqlalchemy_models import LLMUsage, Messages, OnlineTime
+from src.common.database.compatibility import db_get, db_query, db_save
+from src.common.database.core.models import LLMUsage, Messages, OnlineTime
 from src.common.logger import get_logger
 from src.manager.async_task_manager import AsyncTask
 from src.manager.local_store_manager import local_storage