InvoiceSeller.bankDetails becomes iban/bic (EN16931 wants discrete
PaymentMeans data, not a paragraph a human formatted by hand). The
footer's bank-details line also drops the misleading "(für Überweisung)"
qualifier — it was never actually conditional on the order's payment
method (only on whether the field was set at all), just worded as if it
were. Now shown whenever iban or bic is set, regardless of payment
method.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Consolidates code previously hand-duplicated between the einfach-produktiv
frontend and payload backend repos into one canonical implementation,
consumed as a git dependency by both instead of being kept in sync by eye.
While merging the two correction-invoice copies, found and fixed three
real drifts between them:
- variantName was silently dropped in the backend's emailed Stornorechnung/
Gutschrift, but present in the frontend's re-download copy
- the backend's correction-invoice footer wasn't position:fixed, unlike
the original invoice and the frontend's copy
- the backend used a numeric date format (03.07.2025) while the original
invoice and the frontend's copy both used a spelled-out month (03. Juli
2025) — a re-download didn't visually match what was emailed
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Marco