Grokcodile/key54 ? reverse-engineered prompt

Build me a tiny macOS app that lets me bind one app of my choice to the right Command key.

When I hold the right ⌘ key, it should switch to that app, and if I hold it again, it should take me back to the app I was using before. It needs to feel smooth and not break normal right ⌘ shortcuts when I just tap the key quickly, so include a hold delay setting with a few simple presets and a custom option.

I want a small settings window where I can pick the app, choose how long the key needs to be held, and pick between two simple animation styles that show the switch happening. It should run quietly in the background with no Dock icon or menu bar item, and start automatically when I log in.

Make it work well with full screen apps too, and ask for Accessibility permission so it can detect the key properly. If you need to look up current macOS docs or best practices, go ahead.