fix(ci): Update frontend test to match new UI

Author: subha0319

frontend/src/App.test.js

@@ -1,8 +1,8 @@
 import { render, screen } from '@testing-library/react';
 import App from './App';
 
-test('renders learn react link', () => {
+test('renders the main application header', () => {
   render(<App />);
-  const linkElement = screen.getByText(/learn react/i);
-  expect(linkElement).toBeInTheDocument();
-});
+  const headerElement = screen.getByText(/Huffman Coding Visualizer/i);
+  expect(headerElement).toBeInTheDocument();
+});