lj-expand/lj-expand ? reverse-engineered prompt

Build me a modified LuaJIT based tool for 64 bit Garry’s Mod that lets me run my own Lua code more freely on my own machine for testing and auditing.

I want it to feel like a real fork of LuaJIT, with the code organized cleanly, the build working from the repo, and the docs making it clear how to compile and use it. Please make the project usable on Windows with a simple build flow, and keep the implementation focused on the Lua runtime changes needed for Garry’s Mod 64 bit support. If anything depends on current upstream docs or build steps, look them up online and keep the README helpful for getting started.

Also make sure the project is easy to inspect and maintain, since I may want to tweak the runtime later.