[Feature Request] Support sending email attachments via hey compose

[geonizeli]

It would be great if HEY CLI supported sending email attachments.

At the moment, it appears possible to compose and send emails from the CLI, but not include attachments such as PDFs, images, reports, or other files. This limits automation workflows that generate files and need to email them directly.

Being able to send emails with attachments would make the CLI significantly more useful for scripting and operational tasks.

Thanks for considering it.