Karte 10: Kamera-Scan im Frontend (Objekt-Code, Scan-First-Einstieg)

BarcodeScanner-Komponente auf @zxing/browser (Code128, iOS/Safari-kompatibel
im Gegensatz zur nativen BarcodeDetector-API). Treffer springt direkt ins
Kontroll-Screen, sonst Fallback ins bestehende Such-Textfeld.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CVgbozhYmuEhiEJHffRXCV

frontend/src/styles/global.css

@@ -321,3 +321,27 @@ select.input:focus {
 .section {
   margin-bottom: 2rem;
 }
+
+.scanner-overlay {
+  position: fixed;
+  inset: 0;
+  background: rgba(0, 0, 0, 0.85);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 100;
+}
+
+.scanner-box {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 0.5rem;
+  padding: 1rem;
+}
+
+.scanner-video {
+  width: min(90vw, 480px);
+  border-radius: 0.5rem;
+  background: #000;
+}