Create a new user from a Strava login

Closing as won't fix.

Auto-creating a Drupal user from an anonymous Strava login is not something we can support properly. Since the authentication and scope change in #3007441, the Strava API no longer exposes the athlete's email address, and there is no scope that returns it.

We could technically create an email-less account keyed on the Strava athlete id, but that account would be second-class in Drupal:

• No password reset or one-time login (there is no email to send to).
• No email notifications of any kind.
• Open auto-registration from a third party is a spam and abuse vector.

Instead of auto-creating accounts, the supported flow is now "link, don't create": a visitor registers or logs into Drupal normally, then connects their Strava account while authenticated. That path needs no email address.

• #3611219 wired AthleteManager::createAthlete() into AthleteUserHandler::connect(), so the athlete entity is now created on first connect for an authenticated user (and re-linked rather than duplicated on reconnect).
• #3611131 removed the leftover email-based registration code (UserManager::registerUser(), getUserByEmail(), AthleteUserHandler::userExists() / userCreate()) that this feature used to depend on.

If a site genuinely needs "sign in with Strava" style account creation, that is better handled by a dedicated external-auth integration (for example a contrib OAuth login bridge) rather than by this module fabricating email-less accounts.

Documented in code that anonymous auto-registration is intentionally unsupported because this is not possible with the Strava API (no email).