RfidResearchGroup/ChameleonUltra — reverse-engineered prompt

I want this repo turned into a working Chameleon Ultra setup that I can actually use with the hardware. Please build the firmware for the NRF52840 based device, make sure the computer side tool in the repo is usable, and leave the project in a state where I can flash the device and talk to it from my machine without guessing.

The goal is to support the main things this project is about, reading, writing, emulating, and decrypting supported RFID and NFC cards, especially the types mentioned in the repo like Mifare, NTAG, Ultralight, ISO 14443A, and 125 kHz where applicable. If anything needs configuration, scripts, or build fixes, just do it in the repo.

Also give me a simple getting started flow in the README or a setup note that explains how to build, flash, connect, and run a basic test. If the repo docs are thin, look up the current wiki and official docs online and use that so the final result matches the current project.