Revert "Fixed the remaining Manager runtime coupling."

This reverts commit bc45608023.

src/app/api/auth/[...nextauth]/route.ts

@@ -1,20 +1,3 @@
-/**
- * Business Auth.js is intentionally unavailable in the standalone Manager
- * deployment. Keeping this check before the dynamic import prevents a stale
- * SessionProvider or direct request from initialising Prisma there.
- */
-function managerAuthDisabled() {
-  return process.env.MANAGER_MODE === "true";
-}
+import { handlers } from "@/auth";
 
-export async function GET(request: Request) {
-  if (managerAuthDisabled()) return new Response(null, { status: 404 });
-  const { handlers } = await import("@/auth");
-  return handlers.GET(request);
-}
-
-export async function POST(request: Request) {
-  if (managerAuthDisabled()) return new Response(null, { status: 404 });
-  const { handlers } = await import("@/auth");
-  return handlers.POST(request);
-}
+export const { GET, POST } = handlers;