Native MIFARE Ultralight AES (MF0AES20) support (closes#1057): AES-128 3-pass
auth + protected read, dictionary/manual unlock, key management, write-back
(Keep/Copy Key), emulation, 48-byte secp192r1 originality signature, 3 one-way
counters, config-page decoding, Random ID with real-UID retrieval, and secure
messaging (CMAC) end-to-end for reader + emulator per datasheet 8.8.3.
Hardware-validated on a real MF0AES20 (QA phases P0-P12; see
documentation/MifareUltralightAES_QA.md and MifareUltralightAES_SecureMessaging_QA.md).
On-silicon testing found and fixed a secure-messaging gate: a real card mutes
(times out) rather than NAKs the first plain command in a secure session, so
CMAC now engages on a timeout as well as a NAK.
API 88.2 -> 88.3 (one new symbol, mf_ultralight_aes_get_key).
