refactor: 重构RAG核心组件，简化代码结构和测试文件

backend/app/main_graph/nodes/rag_nodes.py

@@ -19,7 +19,7 @@ from app.main_graph.utils.retry_utils import (
 )
 
 # 真正导入和利用已有 RAG 代码
-from app.rag.tools import create_rag_tool_sync
+from app.rag.tools import create_rag_tool
 from app.rag.pipeline import RAGPipeline
 
 

backend/app/main_graph/utils/rag_initializer.py

@@ -1,6 +1,6 @@
 # app/rag_initializer.py
-from app.rag.tools import create_rag_tool_sync, create_rag_tool_async
-from rag_core import create_parent_retriever
+from app.rag.tools import create_rag_tool
+from app.rag.retriever import create_parent_hybrid_retriever
 from app.model_services import get_embedding_service
 from app.logger import info, warning
 
@@ -10,18 +10,18 @@ async def init_rag_tool(local_llm_creator):
         info("🔄 正在初始化 RAG 检索系统...")
         # 使用统一的嵌入服务获取接口
         embeddings = get_embedding_service()
-        retriever = create_parent_retriever(
+        retriever = create_parent_hybrid_retriever(
             collection_name="rag_documents",
             search_k=5,
             embeddings=embeddings
         )
         rewrite_llm = local_llm_creator()
-        rag_tool = create_rag_tool_async(
+        rag_tool = create_rag_tool(
             retriever, rewrite_llm,
             num_queries=3, rerank_top_n=5
         )
-        info("✅ RAG 检索工具初始化成功（异步版本）")
+        info("✅ RAG 检索工具初始化成功（全异步版本）")
         return rag_tool
     except Exception as e:
         warning(f"⚠️ RAG 检索工具初始化失败: {e}")
-        return None
+        return None