feat(memory): add protected memory config deletion with end-user safeguards

- Add force parameter to delete_config endpoint for controlled deletion of in-use configs
- Implement MemoryConfigService.delete_config with protection against deleting default configs
- Add validation to prevent deletion of configs with connected end-users unless force=True
- Reorganize controller imports to remove duplicates and improve maintainability
- Clean up unused database connection management code from memory_storage_controller
- Add detailed docstring to delete_config endpoint explaining protection mechanisms
- Update error handling with specific BizCode.RESOURCE_IN_USE for configs in active use
- Add comprehensive logging for deletion attempts, warnings, and affected users
- Refactor ConfigParamsDelete schema usage to use MemoryConfigService directly
- Improve API response structure with affected_users count and force_required flag

api/app/models/memory_config_model.py

@@ -1,6 +1,8 @@
 import datetime
-from sqlalchemy import Column, String, Boolean, DateTime, Integer, Float
+
+from sqlalchemy import Boolean, Column, DateTime, Float, Integer, String
 from sqlalchemy.dialects.postgresql import UUID
+
 from app.db import Base
 
 
@@ -38,6 +40,7 @@ class MemoryConfig(Base):
 
     # 状态配置
     state = Column(Boolean, default=False, comment="配置使用状态")
+    is_default = Column(Boolean, default=False, comment="是否为工作空间默认配置")
 
     # 分块策略
     chunker_strategy = Column(String, default="RecursiveChunker", comment="分块策略")