Server storage related code shouldn't be named "app"

Just a quick bug report. The current server-side storage uses code from a folder called `app`. The import for it in `server.py` is `from app.user_manager import UserManager`.

The issue with this is that a lot of ML projects already install as generic names such as "app" or "library", meaning it's possible to have a conflict between a system level package and the local file. This will cause an import error in most cases.

The easiest solution - in my opinion - is to simply give it a more descriptive name.

Here is an example of running the latest commit in a conda env that is shared between comfy and [audiocraft](https://github.com/facebookresearch/audiocraft) installed via `pip install -e .`