Add chatbot experience

[lambdakris]

We should add a basic chatbot experience to the frontend. The chatbot should be similar to what is described in this streamlit tutorial. We should stub the LLM call just like in the tutorial and focus just on the UI/UX. The streamlit code should be well factored and modular, such that it is easy to read and find where in the code things are rendered and/or events are handled.