Change QR-Code function label from "2D-Code" back to "QR-Code"

The function keeps reading all 2D-code types (QR-Code, MicroQRCode, RMQRCode,
DataMatrix, Aztec, PDF417) as requested. The label is now "QR-Code" per the
client's preference for their terminology. Added clarifying comments explaining
the intentional mismatch between the name and the supported formats, since the
hardware labels use DataMatrix (not QR). Updated README and test accordingly.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

test/scan-modes.test.js

@@ -17,9 +17,9 @@ test('Funktion 1 (Strichcode): eindimensionale Codearten, laufende Suche, keine
   assert.equal(mode.useOcr, false);
 });
 
-test('Funktion 2 (2D-Code): QR-Varianten und DataMatrix, Aztec, PDF417', () => {
+test('Funktion 2 (QR-Code): QR-Varianten und DataMatrix, Aztec, PDF417', () => {
   const mode = getScanMode('qrcode');
-  assert.equal(mode.label, '2D-Code');
+  assert.equal(mode.label, 'QR-Code');
   assert.deepEqual(mode.barcodeFormats, [
     'QRCode', 'MicroQRCode', 'RMQRCode', 'DataMatrix', 'Aztec', 'PDF417',
   ]);