- supplier/buyer: extract FC tax registration (BT-32/BT-49) into new
tax_number field; previously only VA (USt-IdNr.) was read
- pflichtfelder: critical error only when neither vat_id nor tax_number
is present (EN 16931 BR-CO-26)
- ustid: tolerate formatting whitespace inside VAT IDs (e.g. 'DE 140 978 617')
- line items: normalize unit price by basis quantity (BT-149), so a
price per 100 units no longer inflates line totals by factor 100
- supplier email: also look in DefinedTradeContact (BT-42)
- rewrite xrechnung fallback test to assert only our own behavior,
independent of factur-x version specifics
m3ta-chiron