fix(providers): stop requesting unapproved Fortnox scopes that broke every connect (#1549)

PR #1541 added archive and connectfile to the Fortnox DEFAULT_SCOPES for
the voucher attachment import, but the registered Fortnox app does not
have those scopes approved in the Fortnox Developer Portal. Fortnox
rejects the authorize request with invalid_scope before login, which
broke every Fortnox connect in production within minutes of the deploy
(verified in Vercel runtime logs).

Remove the two scopes from the connect request; the attachment import
logic from #1541 stays fully intact and already degrades gracefully:
a 403 becomes PROVIDER_DOCUMENT_SCOPES_REQUIRED with a reconnect
follow-up card. Re-add the scopes once the portal registration has them
approved.

Also add charset=utf-8 to the OAuth callback HTML responses: without it
browsers render the Swedish error text as Latin-1 mojibake.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

extensions/general/arcim-migration/index.ts

@@ -541,7 +541,9 @@ export const arcimMigrationExtension: Extension = {
 
           return new Response(html, {
             status: 200,
-            headers: { 'Content-Type': 'text/html' },
+            // charset is required: without it browsers default to Latin-1 and
+            // render the Swedish text as mojibake (the "rätt behörigheter" bug).
+            headers: { 'Content-Type': 'text/html; charset=utf-8' },
           })
         }
 
@@ -622,7 +624,9 @@ export const arcimMigrationExtension: Extension = {
 
           return new Response(html, {
             status: 200,
-            headers: { 'Content-Type': 'text/html' },
+            // charset is required: without it browsers default to Latin-1 and
+            // render the Swedish text as mojibake (the "rätt behörigheter" bug).
+            headers: { 'Content-Type': 'text/html; charset=utf-8' },
           })
         } catch (error) {
           log.error('OAuth callback exchange failed', error)