Fix barcode scanner on iOS Safari

iOS WebKit does not provide a reliable native Barcode Detection API, and
ZXing often failed due to strict camera constraints and video startup timing.

- Install @undecaf/barcode-detector-polyfill (ZBar WASM) on Apple devices
- Fall back through progressively looser getUserMedia constraints
- Wait for video metadata/playback before decoding frames
- Throttle native scans on iOS and tune ZXing retry intervals
- Defer scanner startup until the modal video element is mounted

Co-authored-by: Ned Halksworth <hello@nedhalksworth.com>

vite.config.ts

@@ -13,6 +13,7 @@ export default defineConfig(({ command }) => ({
           charts: ["recharts"],
           motion: ["framer-motion"],
           icons: ["lucide-react"],
+          barcode: ["@undecaf/barcode-detector-polyfill"],
         },
       },
     },