Create basic notification scaffolding

[casesandberg]

Utilize resend (the provider we are using for auth) to send transactional emails to users. Some starter emails that could be built include:

• Welcome to Play Money email when a user creates a new account.
• Someone commented on a market you created.
• Someone tagged you in a comment (more advanced).

Would also be cool to look into styling an email template with Tailwind / our tailwind color configs. Nice to have, not a requirement.