Revert "Fixed the remaining Manager runtime coupling."

This reverts commit bc45608023.

src/components/manager-providers.tsx

@@ -1,9 +0,0 @@
-import type { ReactNode } from "react";
-
-/**
- * Manager authentication uses its own signed cookie. This provider is kept
- * free of next-auth/react so the Manager never polls `/api/auth/session`.
- */
-export function ManagerProviders({ children }: { children: ReactNode }) {
-  return <>{children}</>;
-}