Resolve "get out of dependency hell"

• add nix-based support for non-python deps, with and without CUDA. If having version issues or need to set up new machine, can follow README.
• add missing python dependency bagpy, would prefer to remove this (its heavy, only ROS1, we already have rosbags) but I leave that to you/Lisa
• (as of time of writing) Python3.11, jaxlib w CUDA working on Converging PC

Closes #31 (closed)