feat(auth): implement role-based access control and user management features

frontend/app/api/admin-users/[id]/route.ts

@@ -0,0 +1,27 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { auth } from '../../../../../auth';
+
+const API_BASE =
+  process.env.NEXT_PUBLIC_API_URL_INTERNAL ?? 'http://recipe-api:8080';
+
+export async function PATCH(
+  request: NextRequest,
+  { params }: { params: { id: string } },
+) {
+  const session = await auth();
+  if (!session || (session.user as any)?.role !== 'admin') {
+    return NextResponse.json({ message: 'Förbjuden' }, { status: 403 });
+  }
+
+  const body = await request.json();
+  const res = await fetch(`${API_BASE}/api/users/${params.id}/role`, {
+    method: 'PATCH',
+    headers: {
+      'Content-Type': 'application/json',
+      Authorization: `Bearer ${session.accessToken}`,
+    },
+    body: JSON.stringify(body),
+  });
+  const data = await res.json();
+  return NextResponse.json(data, { status: res.status });
+}