Improve the email confirmation user flow

Is your feature request related to a problem? Please describe.
After completing the sign up form the user is redirected to the homepage where a green banner appears prompting users to confirm their email address clicking on the link the platform sent.

During user testing we identified a couple pain points :

Don’t understand that they need to confirm their email

Some users don’t read the banner as they interpret the green color as a success message that they are loggued in and start scrolling down. Later when they want to start interacting (creating a proposal for example) some get stuck as they don’t understand why the platform asks them to login and do not think of checking their email to click on the confirmation link.

Inputed the wrong email

The alert banner does not say to which email the confirmation link was sent. If the user made a mistake when inputing their email they have no way to find out after sending the form. Many do not assume they made a mistake and blame it on the platform. We’ve received many support ticket with users saying they do not receive the email, that it must be in their spam folder.

Need to login after email confirmation

When the user clicks on the confirmation link she’s redirected to the home page with a green alert message saying they successfully confirmed their email.

This adds an extra step that can annoy or confuse users.

As stated above some users think they just logged in and are surprised that when interacting with the platform we ask them to login.

Describe the solution you'd like
Our solution consist of two things :

• Adding a dedicated email confirmation page with useful info ;
• Use a confirmation code instead of a confirmation link so the user can finalize sign up on the same page as they started and be redirected as logged in on the page they began with ;

As a user, right after completing the sign up form, I should be redirected to dedicated page for email confirmation where :

• I’m given clear instruction to validate my account
• I can see the email I used to sign up (and see if I made a typo)
• I can input the confirmation code I received
• I can read a troubleshoot section
• I didn’t receive the email
• I inputed the wrong email
• How to resend the confirmation email
• I can read about the benefits of confirming my email :
• Participate in processes : add a proposal, vote, comment etc.
• 
  
• Interact with other participants : send them messages, follow them etc.

Describe alternatives you've considered
Using magic links for login.

Additional context
This is linked to issue https://github.com/decidim/decidim/issues/8423 and this unfinished PR https://github.com/decidim/decidim/pull/8496 (External link) (External link)
This proposal is part of a larger scope to improve authentication flow in Decidim. Working document here

Does this issue could impact on users private data?
No

Funded by
OSP and Angers