PDL Person Enrich — career history, emails, phone. Requires one of: `email`, `profile` (LinkedIn URL), or `first_name` + `last_name` + (`company_name` OR `company_domain`). `{ first_name, last_name }` alone returns 400. Prefer `email` when known, then `profile`. No match: HTTP 200, status 404, data null — not billed. Match: $0.28.