The seeds file was creating an unconfirmed user and then setting a password,
which conflicts with Phoenix's auth system (magic link login is not allowed
for unconfirmed users with passwords).
This fix ensures the demo user is confirmed before setting their password,
so they can log in via both magic link and password.
Demo credentials: demo@example.com / password123!
Goal: have a personal blog, and try out another point in the 'modular
app design with elixir' space.
Designing OTP systems with elixir had some interesting ideas.