Scale & Barcode Label Support

Added new scale options for NeroPOS. Merchants can now choose between Off, Manual Barcode Label scanner, or Automatic USB/COM Serial scale mode from NeroPOS settings. Manual barcode label mode allows staff to scan scale-printed barcodes directly into the POS search box, automatically adding the matching weighted product to the basket. Product Advanced Weight Price settings were added for PLU/product code, barcode support, and unit configuration. Automatic scale mode prepares NeroPOS for USB/COM serial scale integration. Improved settings layout and fixed product edit display issues related to the new scale fields.