BuylistOrder Creation

How buy orders create BuylistOrder records.

• Order Type: Creates BuylistOrder (not POSOrder) when buyMode flag is true
• Order Status: Orders created as "pending_approval" by default
• POS Snapshot: Complete snapshot of POS transaction saved in order
• Payment Details: Records cash and store credit amounts paid
• Cart Items: Converts line items to buylist cart format
• Vendor Tracking: Links order to vendor customer record
• Source Tracking: Marks order as "pos" source with posBuy flag