refactor: reorganize import statements for Calculator tool

app.py

@@ -6,10 +6,10 @@ import requests, textwrap
 
 from langchain_huggingface import ChatHuggingFace, HuggingFaceEndpoint
 
-from langchain_community.tools import DuckDuckGoSearchRun, Calculator
+from langchain_community.tools import DuckDuckGoSearchRun
 from langchain.agents import initialize_agent
 from langchain_core.prompts import ChatPromptTemplate
-from langchain_community.tools import Calculator
+from langchain_community.tools.calculator.tool import Calculator
 
 
 # --- Constants ---