更新KGManager和知识库配置，统一使用global_config的lpmm_knowledge属性，移除未使用的MemoryActiveManager导入

src/chat/knowledge/mem_active_manager.py

@@ -1,3 +1,4 @@
+raise DeprecationWarning("MemoryActiveManager is not used yet, please do not import it")
 from .lpmmconfig import global_config
 from .embedding_store import EmbeddingManager
 from .llm_client import LLMClient