Turn this into a python package

Making this into a python package will be great.
If all is needed for installation is `pip install screenshottocode`,
and then just running `screenshottocode` starts the application,
it will make it easier to use this project.
I can work on that if you want.

The frontend will just have to be built before publishing the whole application.

I've already added gemini pro vision support and made a pull request.
I hope it get's merged.