Frizti/Lichii ? reverse-engineered prompt

Build me the Lichii project from this repo so it actually compiles and runs cleanly from a fresh clone.

Keep it aligned with the existing C++ codebase and CMake setup, use the bundled extras and tools where needed, and make sure any missing pieces are filled in in the simplest way that fits the current project. If there are NX2 specific notes or GPU thread split details that matter, follow those. I want a working result, plus clear build and run instructions, and any small fixes or docs updates needed so someone can get it going without guesswork.

Please clean up obvious rough edges too, and if you need current docs or references, look them up online.