Interrupt token generation #187

Hi, thanks for the development of this wonderful and very promising app.

often the LLM generates a lot of tokens that you finally don't want, either after a prompt that was badly formulated or because it is resoning in the wrong direction. That can take a while, waste computing energy and pollute the discussion. Most chat interface have a "stop" button to interrupt it, but I haven't found one in the BTW shiny app.
I think it would be a very convenient addition for every user.

Regards