Order line reference support

You can now include order line references on invoice and credit note line items, making it easier to track which purchase order lines correspond to each invoice line.

What changed

• Order line reference field: Added optional orderLineReference field to invoice and credit note line items
• UBL support: Order line references are included in the generated UBL XML and parsed from incoming documents
• Bidirectional support: Works for both sending and receiving documents

Why this matters

Order line references are essential for:

• Purchase order tracking: Link invoice lines back to specific lines in purchase orders
• Better traceability: Track which order line each invoice line corresponds to
• Automated reconciliation: Help systems automatically match invoices to purchase orders
• Compliance: Meet requirements for referencing purchase orders in invoices

This update improves traceability and helps with purchase order reconciliation workflows.