fix: konvertera alla API route handlers till withAuth wrapper

Ersätter getAuthHeaders() + auth() standalone med withAuth() wrapper
i alla route handlers. Auth() standalone fungerar inte korrekt i
Next.js 16 + NextAuth beta.28 pga async cookies() kompatibilitet.
withAuth() använder auth() i wrapper-form sa att request.auth
populeras direkt av NextAuth.

Pavaerkade filer: 27 route handlers + ny lib/with-auth.ts

frontend/app/api/quick-import-proxy/route.ts

@@ -1,35 +1,30 @@
-import { NextRequest, NextResponse } from 'next/server';
-import { getAuthHeaders } from '../../../lib/auth-headers';
+import { NextResponse } from 'next/server';
+import { withAuth } from '../../../lib/with-auth';
 
-export async function POST(request: NextRequest) {
+export const POST = withAuth(async (request, session) => {
   try {
     const contentType = request.headers.get('content-type') ?? '';
     const isMultipart = contentType.includes('multipart/form-data');
     const backendUrl = process.env.NEXT_PUBLIC_API_URL_INTERNAL || 'http://recipe-api:8080';
-    const authHeaders = await getAuthHeaders();
 
     const response = await fetch(`${backendUrl}/api/quick-import`, {
       method: 'POST',
       body: isMultipart
         ? await request.formData()
         : JSON.stringify(await request.json()),
-      headers: isMultipart ? { ...authHeaders } : { 'Content-Type': 'application/json', ...authHeaders },
+      headers: isMultipart
+        ? { Authorization: `Bearer ${session.accessToken}` }
+        : { 'Content-Type': 'application/json', Authorization: `Bearer ${session.accessToken}` },
       cache: 'no-store',
     });
 
     const text = await response.text();
-
     return new NextResponse(text, {
       status: response.status,
-      headers: {
-        'Content-Type': response.headers.get('content-type') ?? 'application/json',
-      },
+      headers: { 'Content-Type': response.headers.get('content-type') ?? 'application/json' },
     });
   } catch (error) {
     console.error('[QuickImportProxy] EXCEPTION:', error);
-    return NextResponse.json(
-      { message: 'Kunde inte nå importtjänsten.' },
-      { status: 503 },
-    );
+    return NextResponse.json({ message: 'Kunde inte nå importtjänsten.' }, { status: 503 });
   }
-}
+});