This update adds three new fields – Buyer Reference, Contract Reference, and Purchase Order Reference – to the invoice PDF generated by the l10n_fr_facturx_chorus_pro module. These fields are required for Chorus Pro compliance, ensuring invoices meet the necessary documentation standards for this specific accounting system.

This commit:
- Add three reference fields to invoice PDF for Chorus Pro compliance: Buyer Reference, Contract Reference, and Purchase Order Reference. These fields appear in the invoice header when set on the invoice.

task-5410836