MfWhitelistApiClient.lookupByNip() exposes is_jdg/krs from MF Biala Lista.
InvoiceController.nipLookup propagates is_jdg in JSON response.
invoice_form.php JS conditionally targets buyer_name (JDG) or
buyer_company_name (spolka z KRS); second field keeps zamowienie pre-fill.
Fixes apparent field swap on /orders/{id}/invoice/create after GUS lookup
for JDG (sole trader) where MF returns natural person in subject.name.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>