Add barcode scanner integration, identifier lookup, and enhanced field mapping for label creation

src/styles/app.css

@@ -791,6 +791,36 @@ button.legend-card:focus-visible {
   cursor: pointer;
 }
 
+.scanner-modal-backdrop {
+  position: fixed;
+  inset: 0;
+  z-index: 1100;
+  display: grid;
+  place-items: center;
+  padding: 1rem;
+  background: rgba(16, 24, 40, 0.62);
+  backdrop-filter: blur(2px);
+}
+
+.scanner-modal {
+  width: min(40rem, 100%);
+  border-radius: 1rem;
+}
+
+.scanner-video-shell {
+  border-radius: 0.85rem;
+  overflow: hidden;
+  border: 1px solid rgba(31, 75, 153, 0.2);
+  background: #0f172a;
+}
+
+.scanner-video {
+  display: block;
+  width: 100%;
+  aspect-ratio: 16 / 10;
+  object-fit: cover;
+}
+
 @media (max-width: 991.98px) {
   .navbar {
     backdrop-filter: blur(10px);
@@ -804,4 +834,15 @@ button.legend-card:focus-visible {
   .empty-preview {
     border-radius: 1.25rem;
   }
+
+  .scanner-modal-backdrop {
+    align-items: end;
+  }
+
+  .scanner-modal {
+    width: 100%;
+    margin-bottom: 0.75rem;
+    border-bottom-left-radius: 0;
+    border-bottom-right-radius: 0;
+  }
 }