Show an example of using prompt-garden as a runtime

[jkomoros]

Prompt garden can be used as a CLI or in the demo web app, but it can also be used to power a simple webapp where it uses it to run simply configured code.

Have a very simple example that someone lightly technical could tweak and then mostly just plug in their own seeds and environment.

• [x] Publish the main files and entrypoints to npm
• [x] Create a new simple repo with example