atmosphere-nx/atmosphere ? reverse-engineered prompt

Build me a clean, working build of Atmosphère from this source tree.

I want the project to compile reliably, with the main firmware components wired up so it can be packaged and tested from source without me having to figure out a bunch of missing steps. Make sure the build instructions are clear, any broken or outdated docs are fixed, and if there are obvious gaps in configuration or templates, fill them in with sensible defaults.

If something depends on current external docs or toolchain details, look those up online and use the latest correct guidance. Also check for any build issues, missing includes, bad paths, or files that should be generated as part of the process, then fix them.

Please keep the changes focused on getting a successful build and a usable project structure, and update the README only where it helps someone clone the repo and get it working.