Submit Signup Profile

Store the caller's questionnaire answers on their own account.

Rate Limited: 10 requests per minute per IP address.

Questionnaire-free clients never call this route. It remains ungated so an older client already open during the rolling deploy can finish its optional submission after the public signup toggle changes. The write annotates the caller's own existing account and creates nothing; MAIA-4460 removes this compatibility route after the rollout window closes.