Pos_Invoicing

Description:
Implement POS hardware integrations including barcode scanning, receipt printing, and device-level interactions. This includes offline barcode-based product lookup, cart handling, thermal printer support, and GST-compliant receipt generation.

The system must support fast offline operations, accurate invoice printing, and seamless interaction with standard POS hardware like barcode scanners and receipt printers.

Acceptance Criteria:

Barcode scan adds product to cart instantly (offline supported)
Barcode mapped to product and synced to POS
Receipt printing works offline and matches invoice data
Thermal printer (80mm) supported
GST details correctly printed (CGST/SGST/IGST)
Printer failures handled without data loss