pqrs-org/Karabiner-Elements ? reverse-engineered prompt

Build me a macOS app that lets me remap my keyboard keys in a powerful but easy way.

I want to be able to change one key into another, make different rules for different keyboards, and have it run in the background on modern macOS versions. It should feel like a real utility app, with a simple setup flow, settings screens, and clear prompts for the permissions it needs, like accessibility and background service access.

Please make it so the app can be packaged and installed like a normal Mac app, and if anything needs code signing or special build steps, set that up too. If you need to check current Apple docs or build requirements while working, go ahead and look them up online. I mainly want a working app that can be installed and used to customize my keyboard behavior on macOS.