Edit usernames and email addresses for ahead ID users

Confirmation and automatic notifications
Username and email changes are confirmed in a dedicated dialog before they take effect. When a change affects how a user signs in or where ahead sends their communications, the user is automatically notified by email. The notification is sent in the user's preferred language, or in a language the admin selects if none is set.

Reissue onboarding after a username change
For users who haven't onboarded yet, changing the username resets their pending invitation. The admin reissues it with "Start onboarding" once ready, so the user completes onboarding with the new username.