Include identity.id in the my/identity.json response and return an
empty body from the CREATE signup/completions.json endpoint.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The magic link verification endpoint now returns `requires_signup_completion`
to indicate whether the client needs to collect a name and complete signup.
The signup completion endpoint now supports JSON responses with the account ID.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>