Looks up a customer by the passport number encoded in an 88-character passport machine-readable zone (MRZ, ICAO TD3 two-line format). Returns the existing customer if one matches the passport number, otherwise creates a customer from the MRZ data (name, birthday, passport number, plus parsed details in meta). Requires the p/c-customer permission. The passport-number check digit is verified; an invalid MRZ fails with 400 BAD_REQUEST.