Add edit buzzwords functionality

[jtaavola]

resolves #13

This adds an edit modal to customize the buzzwords! It lists all the buzzwords in a big text area and allows you to customize them by adding one buzzword per line.

We can iterate on this to make it better, i.e. upload from file, save updates to local storage (#19), etc.

You might need to do npm install to test this out since I added some dependencies.

[jtaavola]

Looks great! If we're using Mantine, we should use it for everything else for consistency, but we can do that in another PR.

Good point, I'll create an issue 👍