/**
 * Reads an environment variable, treating blank as absent.
 *
 * `process.env.X ?? fallback` is not enough: a key that is present but empty
 * - which is how .env.example ships the optional ones, e.g. `SMTP_FROM=` -
 * is an empty string, not undefined, so `??` keeps the empty value and the
 * fallback never applies. That produced an empty From header and port 0.
 *
 * Dependency-free on purpose, so both server.js and emailService.js can use
 * it without dragging nodemailer into the importing module's graph.
 */
export function env(name, fallback = undefined) {
  const value = process.env[name]
  if (value === undefined || value.trim() === '') return fallback
  return value.trim()
}