Add Docker Deployment

[ytausch]

This follow-up PR of #10 is intended to be merged after #10.

In this PR, we add a Docker deployment for the app. The pixi environment is used within the Docker container.
To allow app installation within the container, I restructured the project to be located in a Python module that is installable with pip. Unfortunately, because of limitations imposed by Streamlit, a workaround (app_proxy.py) was required for Streamlit to execute an app from a Python module.

If you want to use the Docker container today, a Docker Image has already been pushed to GHCR in my fork.

diff view for convenience

@pavelzw

[ytausch]

This is the Streamlit Cloud Deployment from my fork, proving that the app_config.py hack works there as well: https://2wmcagxddiqfknnuikwyrq.streamlit.app/

[ytausch]

@pavelzw missing your approval checkmark :)

[ytausch]

I have adjusted the pixi deployment to use conda packages whenever possible. This was necessary because of a pixi bug, and also a good idea in general IMO.

streamlit-searchbox (the last PyPI dependency) is currently awaiting review in staged-recipes:

• add streamlit-searchbox conda-forge/staged-recipes#28067

Otherwise, this is ready for review! @jaimergp

[ytausch]

Since streamlit-searchbox is now on conda-forge, I've adjusted the dependency accordingly.
Unfortunately, there is no conda-oci-mirror on PyPI yet, so I had to use the git URL in pyproject.toml.

[jaimergp]

Thanks!