[RAG] 全部LLM硬编码从deepseek-r1改为deepseek-v3；修复知识库问答source格式不匹配导致检索结果被丢弃

langchain-chat/server/chat/knowledge_base_chat.py

@@ -138,7 +138,7 @@ async def knowledge_base_chat(query: str = Body(..., description="用户输入",
         if isinstance(max_tokens, int) and max_tokens <= 0:
             max_tokens = None
         if prompt_name == "policy_chat":
-            model_name = LLM_MODELS[1]
+            model_name = LLM_MODELS[0]
         model = get_ChatOpenAI(
             model_name=model_name,
             temperature=temperature,