Feature/memory work (#61)

* refactor(conversation): separate service and repository layers for conversation module

- Split ConversationService and repository/UnitOfWork layers
- Service layer now only handles business logic and orchestration
- Repository layer handles all direct database operations
- UnitOfWork encapsulates transactional operations for messages
- Ensured all public methods have clear English docstrings with arguments, return values, and exceptions

* feat(memory): implement work memory endpoints and services

- Added API routes for conversation count, conversation list, messages, and detail.
- Integrated ConversationService for database queries and LLM-based summary generation.

* feat(memory): implement work memory endpoints and services

- Added API routes for conversation count, conversation list, messages, and detail.
- Integrated ConversationService for database queries and LLM-based summary generation.

* feat(workflow): fix issues causing workflow failures

if-else None value error
knowledge empty list rerank
end node output none node value
assigner input none value

* feat(memory): convert memory file creation time to timestamp and include title and first-line fields in file type

* fix(memory): fix serialization output and default value issues

* fix(workflow): fix issue with hybrid search logic in knowledge retrieval node

api/app/controllers/__init__.py

@@ -40,7 +40,8 @@ from . import (
     workspace_controller,
     memory_forget_controller,
     home_page_controller,
-    memory_perceptual_controller
+    memory_perceptual_controller,
+    memory_working_controller,
 )
 
 # 创建管理端 API 路由器
@@ -82,5 +83,6 @@ manager_router.include_router(memory_forget_controller.router)
 manager_router.include_router(home_page_controller.router)
 manager_router.include_router(implicit_memory_controller.router)
 manager_router.include_router(memory_perceptual_controller.router)
+manager_router.include_router(memory_working_controller.router)
 
 __all__ = ["manager_router"]