Initial barcode scanner webapp

Camera-based barcode scanner using ZXing for decoding. Requests wide
video (256x2048), rotates to landscape for decoding, applies contrast
boost and tries both HybridBinarizer and GlobalHistogramBinarizer.
Includes camera selector, manual/auto focus controls, and focus slider.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,7 @@
+{
+	"name": "phone-barcode",
+	"version": "1.0.0",
+	"dependencies": {
+		"@zxing/library": "0.19.2"
+	}
+}