Read a Factur-X / ZUGFeRD invoice: send PDF bytes or a JSON { url }. Extracts the embedded EN 16931 CII into normalised data — seller, buyer, lines, VAT, totals, payment, dates, references — with the detected profile. The read side of e-invoicing (the FR mandate starts with reception). No embedded CII → { profile:"none", warning:"no_embedded_cii" }. ?attest=1 → Ed25519-signed.