ntag: add write/read commands with NDEF support, fix false-OK on mfu wrbl

[nieldk]

Adds NDEF write and read support for NTAG21x tags (213/215/216), and fixes
a silent write failure bug affecting both ntag write and hf mfu wrbl.

New commands

ntag write – writes NDEF records to an NTAG21x tag
--uri URI record (e.g. https://sec1.dk)
--text [--lang] Plain text record with language code
--name [...] vCard 3.0 contact record
--ssid --pass Wi-Fi credential record (WFA WSC)
--hex Raw NDEF message (hex)

ntag read – reads and decodes NDEF records from an NTAG21x tag
--dump Also print raw page hex dump

New file: script/ntag_ndef.py
NDEF encoder/decoder for URI, Text, vCard, Wi-Fi, and raw records.
URI prefix compression per NFC Forum URI RTD spec (prefix table 0x00-0x23).
Wi-Fi uses WFA WSC TLV format, readable by Android and iOS natively.

Bug fixes

• hf mfu wrbl and ntag write both checked if resp: to determine write
  success. Response has no bool, so this was always True regardless of
  whether the card accepted the write. Fixed to check resp.data[0] == 0x00
  (PN532 InDataExchange error byte). Failed writes now print the error byte.

• pn532_cli_main.py used str.split() to parse the command line, causing
  quoted string arguments (e.g. --text "Hello world") to include the literal
  quote characters in the value. Fixed to use shlex.split().

• NtagWrite and NtagRead added to PN532Capabilities in pn532_enum.py.