Creates or returns the existing legacy identity verification for a Person or Account subject. Account and Person aliases can address the same verification. Responses always retain its canonical persisted subject (Person when a Person owns the legacy identity), regardless of the alias used to create/read it. An Account request does not relabel an existing Person verification or start a separate session. The current bridge always runs the existing enhanced embedded identity flow; tier selection, additional checks, metadata, notification controls, and inline monitoring are not accepted until native V3 identity verification flows are available. Replays with the same Idempotency-Key and subject return the original verification; reusing the key with a different subject returns 409.