Changes

Amazon invoices: match documents by the full number in the description (POReference is 20 chars)

The first credit-memo import showed that POReference cannot carry the key: the
column is 20 chars, so 'DE-CN-AEU-2026-134720' (21) is stored as
'DE-CN-AEU-2026-13472' — the new AP CreditMemo was not recognised as the credit
note's document and the self-heal released its inbox row ('voided').

The importer's description starts with the FULL Amazon number on every document
(active, voided rename, iDempiere's reversal), so that is the primary match key
now; DocumentNo / POReference remain the fallback for documents not created by
the importer. No double booking was possible — the importer's duplicate guard
checks the full DocumentNo.