Restructure project to root layout

src/screens/BarcodeScannerScreen.tsx

@@ -0,0 +1,21 @@
+import { Container, Typography } from '@mui/material';
+import { useState } from 'react';
+import { BarcodeScannerView } from '../components/BarcodeScannerView';
+
+export const BarcodeScannerScreen = () => {
+  const [lastCode, setLastCode] = useState('');
+
+  return (
+    <Container sx={{ py: 4 }}>
+      <Typography variant="h5" gutterBottom>
+        Barcode Scanner
+      </Typography>
+      <BarcodeScannerView onDetected={(code) => setLastCode(code)} />
+      {lastCode ? (
+        <Typography variant="body2" color="text.secondary" sx={{ mt: 2 }}>
+          Last detected: {lastCode}
+        </Typography>
+      ) : null}
+    </Container>
+  );
+};