fix(arsredovisning): unblock the signing flow, accept foreign parent org nr, explain Fortnox underlag failures (#1738)

Batch from a real migration walkthrough (Fortnox -> Accounted, 2026-08-20):

- Årsredovisning: the "Låst version" select was empty with no explanation
  because the only version was a draft and "Lås version för underskrift"
  is disabled while the four Lagstadgade upplysningar checkboxes and the
  content confirmation count as blockers. The select is now disabled with a
  hint that names the blocker count and links to Fullständighetskontroll,
  the four AR-NOTE-*-UNCONFIRMED issues carry remediation text, the lock
  button explains why it is grey, and "Markera som signerad" says what it
  still needs (locked version, bevisreferens, date).
- Moderföretagets org.nr accepts a foreign registration identifier
  (CHE-123.456.789, HRB 12345, 923 609 016); personnummer shapes stay out.
- Fortnox underlag discovery: log status, body and Fortnox's message on
  failure, show the message in the UI, treat a 400 with behörighet/scope
  text as scopes-required, and fall back to an unfiltered
  voucherfileconnections list when the financialyear filter answers 400.
- Kontomapping: the Momskod column had min-w only; table-fixed collapsed it
  and its selects overflowed into Konfidens. Real w-72 now.
- SIE import warnings pluralise correctly for one skipped voucher; the
  Verifikationsserie option says the source series is preserved.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

components/extensions/general/ArcimMigrationWorkspace.tsx

@@ -1069,6 +1069,7 @@ function OptionsStep({
   onStart: () => void
   onBack: () => void
 }) {
+  const t = useTranslations('extensions')
   const [showConfirm, setShowConfirm] = useState(false)
 
   const toggleOption = (key: keyof MigrationOptions) => {
@@ -1155,7 +1156,7 @@ function OptionsStep({
               <div className="flex items-center gap-3 border-t border-border py-3">
                 <div className="min-w-0 flex-1">
                   <p className="text-sm font-medium">Verifikationsserie</p>
-                  <p className="mt-0.5 text-xs text-muted-foreground">Serie för importerade verifikationer</p>
+                  <p className="mt-0.5 text-xs text-muted-foreground">{t('ext_arcim_option_series_help')}</p>
                 </div>
                 <Input
                   className="w-16 text-center"
@@ -1597,6 +1598,13 @@ function DocumentImportFollowUp({
             ? t('ext_arcim_documents_discovery_error')
             : t('ext_arcim_documents_import_error')}
       </p>
+      {state.problem?.providerMessage && (
+        <p className="text-xs text-muted-foreground">
+          {t('ext_arcim_documents_provider_message', {
+            message: state.problem.providerMessage,
+          })}
+        </p>
+      )}
       {state.problem?.requestId && (
         <p className="text-xs text-muted-foreground">
           {t('ext_arcim_documents_error_reference', {

components/extensions/general/arcim-document-import-flow.ts

@@ -63,6 +63,8 @@ export interface ArcimDocumentImportProblem {
   requestId: string | null
   reconnectRequired: boolean
   message?: string
+  /** What the source system (Fortnox/Bokio) itself answered, when known. */
+  providerMessage?: string
 }
 
 export function documentOAuthProblemFromReason(
@@ -211,16 +213,25 @@ function problemFromPayload(payload: unknown): ArcimDocumentImportProblem {
   const error = (payload as { error?: unknown } | null)?.error
   const structured =
     error && typeof error === 'object'
-      ? (error as { code?: unknown; requestId?: unknown })
+      ? (error as { code?: unknown; requestId?: unknown; details?: unknown })
       : null
   const code = typeof structured?.code === 'string' ? structured.code : null
   const requestId =
     typeof structured?.requestId === 'string' ? structured.requestId : null
+  const details =
+    structured?.details && typeof structured.details === 'object'
+      ? (structured.details as { providerMessage?: unknown })
+      : null
+  const providerMessage =
+    typeof details?.providerMessage === 'string' && details.providerMessage.trim()
+      ? details.providerMessage.trim()
+      : null
 
   return {
     code,
     requestId,
     reconnectRequired: code === PROVIDER_DOCUMENT_SCOPES_REQUIRED,
+    ...(providerMessage ? { providerMessage } : {}),
   }
 }