Creates email provider instances based on configuration.
Supports automatic provider selection from module options.
Providers are loaded lazily via dynamic imports to avoid pulling in
heavy Node.js-only dependencies (e.g. nodemailer) at module parse time,
which would break Cloudflare Workers and vitest-pool-workers environments.
Email Provider Factory
Creates email provider instances based on configuration. Supports automatic provider selection from module options.
Providers are loaded lazily via dynamic imports to avoid pulling in heavy Node.js-only dependencies (e.g. nodemailer) at module parse time, which would break Cloudflare Workers and vitest-pool-workers environments.