Infra: email services

[tdicks]

Emails are currently sent to the app's log file, which isn't helpful in production.

Prerequisites:

• Move the app to an appropriate domain name (e.g. theheavysessions.org)
• Set up SPF / DKIM / DMARC (and how to set DMARC in a Laravel app)
• (optional) Set up an email service such as Mailgun. Only really needed if we're totally inept at setting up proper email security.

Actions:

• Create a compatible email layout that is brand suitable
• Configure emails in the production .env file
• Add a "Test Email Notifications" button in the user's profile to make sure they get the email.

Next:

• Add email validation to the registration process.

[tdicks]

Moved to Hetzner-based emails, though I think a number are going into junk...