fix(invoices): say what payment detail is missing, per currency (#2126) (#2139)

"Fakturan saknar ett betalningskonto för vald valuta" read as a
foreign-currency account when the invoice was in SEK and the gap was
simply the company's bankgiro; the remediation line also asked for an
IBAN, which SEK does not need. A Visma-migrated user marking invoices
as sent hit this and went looking for a valutakonto.

- describeMissingInvoicePaymentAccount(currency) in
  lib/invoices/payment-accounts.ts: SEK names bankgiro, plusgiro, Swish
  or bank account; other currencies ask for an IBAN account in that
  currency (USD/GBP also offer routing number / sort code + BIC). Both
  point at Inställningar → Fakturering.
- getErrorMessage branches on INVOICE_SEND_PAYMENT_ACCOUNT_MISSING +
  details.currency (every dashboard route already sends it), before the
  English registry shortcut so both locales get the specific text.
- Registry entry rewritten currency-neutral for consumers without
  details (API, MCP): bankgiro/plusgiro/Swish/bankkonto for SEK, IBAN
  otherwise; remediation no longer says IBAN for everything.
- Staged-operation commit path uses the helper directly.

Tests: helper per currency, client mapping sv/en and the no-details
fallback.

Closes #2126


Claude-Session: https://claude.ai/code/session_01WFhSQWzu5SyXB6kG5ActZc

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5.1 <noreply@anthropic.com>

lib/pending-operations/commit.ts

@@ -125,6 +125,7 @@ import { renderToBuffer } from '@react-pdf/renderer'
 import { InvoicePDF } from '@/lib/invoices/pdf-template'
 import { prepareInvoicePdfRender, buildSwishQrDataUrl } from '@/lib/invoices/pdf-render-helpers'
 import {
+  describeMissingInvoicePaymentAccount,
   hasRequiredInvoicePaymentAccount,
   invoiceRequiresPaymentAccount,
 } from '@/lib/invoices/payment-accounts'
@@ -2472,9 +2473,7 @@ async function commitSendInvoice(
   const paymentAccountRequired = invoiceRequiresPaymentAccount(invoice as Invoice)
   if (!hasRequiredInvoicePaymentAccount(company as CompanySettings, invoice as Invoice)) {
     return {
-      error:
-        getErrorEntry('INVOICE_SEND_PAYMENT_ACCOUNT_MISSING')?.message_sv
-        ?? 'Betalningskonto saknas för fakturans valuta.',
+      error: describeMissingInvoicePaymentAccount((invoice as Invoice).currency).sv,
       status: 400,
     }
   }
@@ -2729,9 +2728,7 @@ async function commitMarkInvoiceSent(
 
   if (!hasRequiredInvoicePaymentAccount(settings as CompanySettings, invoice as Invoice)) {
     return {
-      error:
-        getErrorEntry('INVOICE_SEND_PAYMENT_ACCOUNT_MISSING')?.message_sv
-        ?? 'Betalningskonto saknas för fakturans valuta.',
+      error: describeMissingInvoicePaymentAccount((invoice as Invoice).currency).sv,
       status: 400,
     }
   }