[NixOS] [Xfce] chill af setup with custom panel plugin
- desktop environment: [Xfce 4.20](https://xfce.org/)
- window manager: [xfwm4](https://docs.xfce.org/xfce/xfwm4/introduction)
- theme: [Desert-Teal-Dark-40](https://www.pling.com/p/1449286/)
- wm-theme: [X-Aero](https://www.xfce-look.org/p/1016331)
- icons: [elementary](https://github.com/elementary/icons)
- window manager: [xfwm4](https://docs.xfce.org/xfce/xfwm4/introduction)
- theme: [Desert-Teal-Dark-40](https://www.pling.com/p/1449286/)
- wm-theme: [X-Aero](https://www.xfce-look.org/p/1016331)
- icons: [elementary](https://github.com/elementary/icons)