Email field in the registration form allows any input

[HyScript7]

Describe the bug
The frontend's registration form allows any non-blank input for the email.

To Reproduce
Steps to reproduce the behavior:

1. Go to https://memopad.script.projnull.eu/
2. Click on 'Register'
3. Fill out the form, intentionally enter a non-email string into the email
4. Click register

Expected behavior
The site shoudln't let you send the form.

Desktop (please complete the following information):

• Browser: Firefox
• Version: Memopad 1.5.4, Firefox 144.0.2 (Darwin)

Additional context
The site allows sending an invalid email.
This is fine at the moment since the backend doesn't even accept an email field, but would cause issues in the future if #2 is fixed.