Add code versions and short descriptions to the JSON

[dougollerenshaw]

Modify the system prompt to request a code version number and a short description of that version from the LLM. The version number will be matched to the locally saved version of that code (as is the case now, with the version number created locally instead of by the LLM). And the short description will go alongside the version number in the code dropdown.

For descriptions, I have something like this in mind:

• v1: An example plot in matplotlib
• v2: Add axis labels
• v3: Change line color to red

The dropdown in the code popup should include this information.

There should also be a title over the dropdown that says something like "Select code version to view/run".

[dougollerenshaw]

Solved in PR #9 . Closing.