fix: change button type to submit in ChangeAPI component and update temperature unit logic in WeatherData component

frontend/src/components/ChangeAPI.tsx

@@ -64,7 +64,7 @@ const ChangeAPI: React.FC<Props> = ({ currentAPIKey, onClose }) => {
           />
         </div>
         <button
-          type="button"
+          type="submit"
           className="bg-gradient-to-r from-blue-600 to-blue-400 text-white font-bold px-6 py-3 rounded-xl shadow-lg hover:from-blue-700 hover:to-blue-500 transition-all"
           onClick={handleUpdate}
         >