feat: integrate barcode scanning functionality and enhance Appwrite setup

- Added a new `barcode_products` collection to the Appwrite setup for managing barcode data.
- Implemented barcode scanning feature with a dedicated modal for scanning and adding products.
- Introduced new components for barcode product preview and management.
- Updated the setup script to seed verified barcode products from a JSON file.
- Enhanced the application state management to handle barcode-related actions and user interactions.

src/data/barcodes.ts

@@ -0,0 +1,6 @@
+import type { BarcodeSeedProduct } from "../types";
+import verifiedBarcodes from "./verified-barcodes.json";
+
+// Verified retail barcodes only. Add rows here via verified-barcodes.json so
+// the frontend seed data and Appwrite setup script stay aligned.
+export const BUILT_IN_BARCODE_PRODUCTS = verifiedBarcodes as Record<string, BarcodeSeedProduct>;