Update App.tsx

Author: albindavidc

App.tsx

@@ -1,4 +1,4 @@
-import React, { useState, useEffect, useRef } from 'react';
+import React, { useState, useRef } from 'react';
 import { CalculatorMode, HistoryItem, MathResponse } from './types';
 import Calculator from './components/Calculator';
 import AIInterface from './components/AIInterface';
@@ -210,4 +210,4 @@ const App: React.FC = () => {
   );
 };
 
-export default App;
+export default App;