fix(providers): stop the Fortnox reconnect loop, and make the attachment scopes opt-in (#1761)

The Fortnox document import needs the archive and connectfile scopes, which the
registered Fortnox app does not have. Since #1549 pulled them out of the connect
request (they broke every connect with invalid_scope before login), every
attachment call fails and the user was told "Koppla om Fortnox och godkann
behorigheterna", under a button that reruns an authorize URL still not asking
for those scopes. Klura AB followed that loop four times and bought the Fortnox
Arkiv module trying to satisfy it. Prod evidence: no Fortnox attachment has ever
imported, across 166 companies and 24 consents since the feature shipped, and no
live token carries the scopes.

The error and the scope list now derive from one flag,
FORTNOX_DOCUMENT_SCOPES_APPROVED. While it is false a permission failure maps to
a new PROVIDER_DOCUMENT_SCOPES_UNAVAILABLE, which says the permission is missing
on our side, that reconnecting will not help, and that the rest of the migration
came through; the card offers no button, because no user action can succeed.

The attachment scopes also become an opt-in consent rather than part of every
connect. Fortnox derives customer licence requirements from what an integration
requests, so asking everyone for Arkivplats would put a licence in front of
customers who never import a receipt; and keeping it off the default connect
caps the blast radius of a wrong portal registration at the underlag flow rather
than every Fortnox connection. buildFortnoxAuthUrl already took per-call scopes,
provider-client simply never passed any, so this threads documentScopes from
that one button through /connect into the authorize URL.

A document consent is always a superset of an ordinary one: the callback
overwrites the consent's tokens in place, so a narrower grant would revoke the
migration's own ledger access. Pinned by a test that holds either way the flag
is set, alongside one for the 400-with-behorighet answer that six companies hit
between 08-13 and 08-19 and saw only a generic retry for.

Co-authored-by: Jakob Wennberg <311770904+jakobwennberg-oss@users.noreply.github.com>
Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

lib/errors/structured-errors.ts

@@ -2037,6 +2037,13 @@ const PROVIDER_MIGRATION: Record<string, StructuredErrorEntry> = {
     message_en:
       'The Fortnox connection lacks Archive and Connect file access. Reconnect Fortnox and approve those permissions to import documents.',
   },
+  PROVIDER_DOCUMENT_SCOPES_UNAVAILABLE: {
+    httpStatus: 403,
+    message_sv:
+      'Filimport från Fortnox är inte påslagen än: behörigheterna Arkiv och Koppla fil saknas för Accounted-integrationen hos Fortnox. Att koppla om hjälper inte, vi aktiverar det så snart behörigheten är på plats. Allt annat i migreringen är importerat.',
+    message_en:
+      'Fortnox file import is not enabled yet: the Archive and Connect file permissions are missing for the Accounted integration at Fortnox. Reconnecting will not help; we enable this as soon as the permission is in place. Everything else in the migration was imported.',
+  },
   PROVIDER_DISCONNECT_FAILED: {
     httpStatus: 500,
     message_sv: 'Frånkoppling från leverantören misslyckades.',