Hufnagel update feature request: in the file menu, indicate which files are square, and which are hufnagel

Once the Hufnagel mode is implemented, when a user uploads a new file they'll have to choose whether that file should be displayed in square notation or hufnagel notation. I think it'd be useful for file names to somehow indicate which notation they've been uploaded in. This will help users identify files quickly, as well as easily spot when they've uploaded a file in the wrong notation.

One way to distinguish between notations would be with colours: square notation files would be highlighted in one colour, and hufnagel would be highlighted in another colour. These colours could also appear in the upload menu, where the user has to toggle between the two notations. We could then add a little legend at the top of the file menu indicating which colour is which notation. @zih-syuan, what do you think?

@annamorphism do you have any strong feelings about what colours the notations should be? To me, Hufnagel is a sort of pleasing golden yellow and square notation is a nice red, but I'm open to other ideas.