chore: Enhance frontend CI workflow for improved test coverage reporting

### Summary of Changes
- Updated the test command in the CI workflow to use `npx vitest` for running tests with coverage.
- Added a verification step to check for the presence of coverage files (`lcov.info` and `clover.xml`).
- Configured Vitest to output JUnit test results and detailed coverage reports in the specified directory.

### Expected Results
- Improved visibility and reliability of test coverage metrics, facilitating better quality assurance processes.

frontend/vitest.config.js

@@ -7,5 +7,21 @@ export default defineConfig({
     environment: 'jsdom',
     setupFiles: ['./src/setupTests.js'],
     globals: true,
+    reporter: ['verbose', 'junit'],
+    outputFile: {
+      junit: './coverage/test-results.xml'
+    },
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'html', 'lcov', 'clover'],
+      reportsDirectory: './coverage',
+      include: ['src/**/*.{js,jsx}'],
+      exclude: [
+        'src/**/*.test.{js,jsx}',
+        'src/**/*.spec.{js,jsx}',
+        'src/setupTests.js',
+        'src/index.js'
+      ]
+    }
   },
 });