/**
 * Server settings, read from process.env at run time only. Never read secrets
 * through import.meta.env: Vite replaces it at build time and can copy every
 * value, secrets included, into the built bundle. Set variables in the
 * environment (Docker env_file, or the shell when running locally).
 */
export function env(key: string): string | undefined;
export function env(key: string, fallback: string): string;
export function env(key: string, fallback?: string): string | undefined {
  const v = process.env[key];
  return v === undefined || v === "" ? fallback : v;
}