ISO15693 already provides CRC-16 at the transport layer, making
the application-layer CRC redundant. Simplifies header from 6 to
4 bytes, removes crc16_continue/verify_crc, and drops STATUS_BAD_CRC.
Also updates design doc and fixes markdown table formatting.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>