Register a model for Tier 0 Baseline certification

Tier 0 Baseline registration is free of charge, but registration of the model name, model version, and operator is mandatory: a measurement whose model version and accountable operator do not appear in the public registry carries no weight. Rate-limited to 10 requests per 10 minutes per client. Certification is pinned to a model version and attests only to the judgment distribution observed on AIO's formalized items — it is not a legal conformity assessment and not an endorsement by the body that issued any referenced norm. Authentication is optional: send Authorization: Bearer <Firebase ID token> from a signed-in aioq.org account to link the registration to it (operator.email is then forced to the verified account address, and the registration appears at GET /api/me/certifications). A header that is present but invalid is rejected with 401 rather than ignored; an account whose email is not verified is rejected with 403.