fully interactive mode

**Is your feature request related to a problem? Please describe.**

It'd be nice to have the ability to have a full-on "conversation" with Chatify, as opposed to relying solely on canned prompts.

**Describe the solution you'd like**

I'm imagining an additional tab on the Chatify interface that has just a text box (where you can type a question or prompt) and a "submit request" button, like on the other tabs. When you click the submit request, we tweak the prompt a bit behind the scenes to provide a reasonable experience to the user (e.g., we automatically append the code, add some system instructions/context, etc., like we do for the other prompts), and then "submit" (i.e., generate a response to) whatever the user typed.

**Describe alternatives you've considered**

We could also make it easier to define custom prompts, e.g., in a prompts.yaml file that the user can add to the current directory.