Visualization of the ChatTTS codebase

With this PR, I intorduce high-level diagrams for the ChatTTS codebase to help new contributors orient themselves in the codebase. You can see how the proposed changes render here: https://github.com/CodeBoarding/GeneratedOnBoardings/blob/main/ChatTTS/on_boarding.md With over than 4K forks, there are a lot of contributors to the ChatTTS repo. Usually people have a particular change in mind, and now with these diagrams they can immediately identify the component of interest and make the change with the correct context in mind. I'd love to hear where do you stand on diagram first code documentation! I'd usually open a discussion first, but you don't have them enabled for this repo so I decided to go ahead and open a PR. Any feedback is more than welcome! Full transparency: we’re exploring this idea as a potential startup, but we’re still early and figuring out what’s actually useful to developers.