Create or update my customer account

Creates or partially updates the signed-in customer's private profile. The bearer identity and normalized email are authoritative; body fields cannot select another user. A signature-verified AAL1 customer session may create or update the profile when customer MFA is optional; the deployment-wide required mode still enforces AAL2. avatar_url accepts an empty string to remove the photo or a client-cropped square PNG/JPEG/WebP/GIF data URI (at most 300 KB decoded and 512 px per side). Loppee validates the bytes, stores them in private object storage, and returns only a short-lived signed display URL. The avatar-only path cannot create/reactivate an account or change authentication identity, roles, trust, reviews, ranking, or recommendation eligibility. Customer, owner, and admin identities are pairwise exclusive by user id and normalized email.