"We couldn't send an email there" isn't informative enough

[duogenesis]

components/welcome-screen.tsx is where this message is show. There's a few cases to consider:

• HTTP 429 - The message should be "You're doing that too much"
• HTTP 403 - "Account was banned"
• HTTP 4xx - "We couldn't send an email there"
• Other errors - "We couldn't connect to Duolicious"

Make sure to use smart quotes

[duogenesis]

Closed by #288 , #289