Great start. I think you can improve the way you do dialogue, however. It's super easy to just start writing, but for writers who are used to FinalDraft or similar services, there's a more intuitive way to trigger the transition from action lines to dialogue. Maybe add a function that when you hit tab next to an all caps name, it will automatically push it to a dialogue slug (similar to other services). The only way I got it to work was hitting backspace in front of the actual line of dialogue under the name. Quite literally backwards. Also, since this is a new tool, I recommend you add a suggestion / feature request box somewhere very prominent inside the UI for users to submit ideas or feature requests (like the one I just suggested here).
Thank you so much for the review! All really good points, I'll absolutely make the suggestions section more clear and will make improving the issues with the dialogue my top priority :)