Add barcode-detector-api-polyfill dependency and update environment variable declarations in SvelteKit project

src/routes/items/ItemForm.svelte

@@ -50,17 +50,30 @@
     skuValue = defaultSku;
   });
 
-  const hasBarcodeDetector = $derived(typeof globalThis !== "undefined" && "BarcodeDetector" in globalThis);
+  async function ensureBarcodeDetector(): Promise<boolean> {
+    if (typeof globalThis === "undefined" || "BarcodeDetector" in globalThis) return true;
+    try {
+      const mod = await import("barcode-detector-api-polyfill");
+      (globalThis as unknown as { BarcodeDetector: typeof BarcodeDetector }).BarcodeDetector =
+        mod.BarcodeDetector;
+      return true;
+    } catch {
+      return false;
+    }
+  }
 
   async function startScan() {
     scanError = null;
-    if (!hasBarcodeDetector) {
-      scanError = "Barcode scan is not supported in this browser. Try Chrome or Edge.";
+    const hasDetector = await ensureBarcodeDetector();
+    if (!hasDetector) {
+      scanError = "Failed to load barcode scanner. Try again or use Chrome/Edge.";
       showScanner = true;
       return;
     }
     try {
-      stream = await navigator.mediaDevices.getUserMedia({ video: { facingMode: "environment" } });
+      stream = await navigator.mediaDevices.getUserMedia({
+        video: { facingMode: "environment", width: { ideal: 1280 }, height: { ideal: 720 } },
+      });
       showScanner = true;
     } catch (e) {
       scanError = e instanceof Error ? e.message : "Could not access camera.";
@@ -77,23 +90,31 @@
     };
   });
 
+  const SCAN_INTERVAL_MS = 300;
+
   function scanLoop() {
     if (!showScanner || !videoEl || !("BarcodeDetector" in globalThis)) return;
     const detector = new (globalThis as unknown as { BarcodeDetector: typeof BarcodeDetector }).BarcodeDetector();
+    let lastScan = 0;
     async function detect() {
-      if (!showScanner || !videoEl || videoEl.readyState < 2) {
+      if (!showScanner || !videoEl) return;
+      if (videoEl.readyState < 2) {
         scanRAF = requestAnimationFrame(detect);
         return;
       }
-      try {
-        const barcodes = await detector.detect(videoEl);
-        if (barcodes.length > 0) {
-          skuValue = barcodes[0].rawValue;
-          stopScan();
-          return;
+      const now = Date.now();
+      if (now - lastScan >= SCAN_INTERVAL_MS) {
+        lastScan = now;
+        try {
+          const barcodes = await detector.detect(videoEl);
+          if (barcodes.length > 0) {
+            skuValue = barcodes[0].rawValue;
+            stopScan();
+            return;
+          }
+        } catch {
+          // ignore frame errors
         }
-      } catch {
-        // ignore frame errors
       }
       scanRAF = requestAnimationFrame(detect);
     }