Set cookie on redirects if user's old account is banned

functions/api/data-transfers/create.ts

@@ -67,6 +67,7 @@ export async function onRequestPost(context: RequestContext) {
   return new Response(null, {
     headers: {
       location: "/data-transfer/destination-account",
+      "set-cookie": `__dtid=${id}; HttpOnly; Max-Age=3600; Path=/; SameSite=Lax; Secure`,
     },
     status: 201,
   });