/** Browser: `/api/...` (same origin). Server: INTERNAL_API_URL → NEXT_PUBLIC_API_URL → loopback. */
export function apiUrl(path: string): string {
  const p = path.startsWith("/") ? path : `/${path}`;
  if (typeof window !== "undefined") {
    return `/api${p}`;
  }
  const base =
    process.env.INTERNAL_API_URL ||
    process.env.NEXT_PUBLIC_API_URL ||
    "http://127.0.0.1:4000/api";
  return `${base}${p}`;
}