refactor(database): 阶段一 - 创建新架构基础

- 创建分层目录结构 (core/api/optimization/config/utils)
- 实现核心层: engine.py, session.py
- 实现配置层: database_config.py
- 实现工具层: exceptions.py
- 迁移连接池管理器到优化层
- 添加详细的重构计划文档

src/common/database/utils/__init__.py

@@ -0,0 +1,31 @@
+"""数据库工具层
+
+职责：
+- 异常定义
+- 装饰器工具
+- 性能监控
+"""
+
+from .exceptions import (
+    BatchSchedulerError,
+    CacheError,
+    ConnectionPoolError,
+    DatabaseConnectionError,
+    DatabaseError,
+    DatabaseInitializationError,
+    DatabaseMigrationError,
+    DatabaseQueryError,
+    DatabaseTransactionError,
+)
+
+__all__ = [
+    "DatabaseError",
+    "DatabaseInitializationError",
+    "DatabaseConnectionError",
+    "DatabaseQueryError",
+    "DatabaseTransactionError",
+    "DatabaseMigrationError",
+    "CacheError",
+    "BatchSchedulerError",
+    "ConnectionPoolError",
+]

src/common/database/utils/exceptions.py

@@ -0,0 +1,49 @@
+"""数据库异常定义
+
+提供统一的异常体系，便于错误处理和调试
+"""
+
+
+class DatabaseError(Exception):
+    """数据库基础异常"""
+    pass
+
+
+class DatabaseInitializationError(DatabaseError):
+    """数据库初始化异常"""
+    pass
+
+
+class DatabaseConnectionError(DatabaseError):
+    """数据库连接异常"""
+    pass
+
+
+class DatabaseQueryError(DatabaseError):
+    """数据库查询异常"""
+    pass
+
+
+class DatabaseTransactionError(DatabaseError):
+    """数据库事务异常"""
+    pass
+
+
+class DatabaseMigrationError(DatabaseError):
+    """数据库迁移异常"""
+    pass
+
+
+class CacheError(DatabaseError):
+    """缓存异常"""
+    pass
+
+
+class BatchSchedulerError(DatabaseError):
+    """批量调度器异常"""
+    pass
+
+
+class ConnectionPoolError(DatabaseError):
+    """连接池异常"""
+    pass