refactor(knowledge): 移除未使用的HistoryManager类及其引用

清理不再使用的历史管理功能，简化代码结构

server/routers/chat_router.py

@@ -11,7 +11,6 @@ from sqlalchemy.orm import Session
 from pydantic import BaseModel
 
 from src import executor, config
-from src.knowledge import HistoryManager
 from src.agents import agent_manager
 from src.models import select_model
 from src.utils.logging_config import logger

src/knowledge/__init__.py

@@ -1,2 +1 @@
-from .history import HistoryManager
 from .graphbase import GraphDatabase

src/knowledge/history.py

@@ -1,49 +0,0 @@
-from src.utils.prompts import get_system_prompt
-
-class HistoryManager:
-    def __init__(self, history=None, system_prompt=None):
-        self.messages = []
-
-        system_prompt = system_prompt or get_system_prompt()
-        self.add_system(system_prompt)
-
-        if history:
-            self.messages.extend(history)
-
-    def add(self, role, content):
-        self.messages.append({"role": role, "content": content})
-        return self.messages
-
-    def add_user(self, content):
-        return self.add("user", content)
-
-    def add_system(self, content):
-        return self.add("system", content)
-
-    def add_ai(self, content):
-        return self.add("assistant", content)
-
-    def update_ai(self, content):
-        if self.messages[-1]["role"] == "assistant":
-            self.messages[-1]["content"] = content
-            return self.messages
-        else:
-            self.add_ai(content)
-            return self.messages
-
-    def get_history_with_msg(self, msg, role="user", max_rounds=None):
-        """Get history with new message, but not append it to history."""
-        if max_rounds is None:
-            history = self.messages[:]
-        else:
-            history = self.messages[-(2*max_rounds):]
-
-        history.append({"role": role, "content": msg})
-        return history
-
-    def __str__(self):
-        history_str = ""
-        for message in self.messages:
-            msg = message["content"].replace('\n', ' ')
-            history_str += f"\n{message['role']}: {msg}"
-        return history_str