Remove `docker/`

[onkoe]

Goal

Remove unused code from the repo.

Description

Thanks to Pixi and Robostack, we no longer have to use it! ;D

In comparison to Pixi, Docker was always slow, and developing on it over VNC was extremely painful. We can now use our actual hardware as intended.

Checklist

• Remove docker/
• Remove any mentions in docs, if needed.
  • I don't think there are, but...
  • Run a full-workspace search to be sure