Rethink the prompt

One of the main challenges using toolbox is knowing which environment your prompt is in. Our current approach to this:


Various issues here:

- The hexagon:
- It doesn't look great: the colour isn't the best, and it's squashed in before the prompt.
- Why a hexagon? There's no obvious connection to toolboxes. Semantically it's odd.
- It isn't able to differentiate between different toolboxes.
- The prompt just says `toolbox`. Like the hexagon, it doesn't differentiate between toolboxes.

This is a somewhat complicated topic, since we have to think about the overall structure of the prompt. We also maybe need to think about the various tools that exist for doing fancy prompts.