Annotation or Notes Tracks

### Enhancement Summary

An annotation/notes track that can be added to the song-editor just like an instrument track, only holding text information and not contributing any audio or sound data. Hovering over 'bars' of this note track would open a mini-text editor similar to the project notes where the full note could be viewed and edited. Essentially, this is like being able to write notes in the margins of sheet music. Ideally, this would replace or complement the functionality of the Project Notes window.

#### Justification

This would be incredibly helpful for holding lyrics at a certain set of bars in a song, or indicating a key or chord change without having to look at the piano roll for instrument tracks.
I understand that the project notes exist, but I feel that it's a slow and confusing workflow (especially with lyrics) to write down "key change at bar 53", especially if the project is still being written and bar 53 may become bar 41 or something.
Having notes act similarly to instrument tracks with their own bars in the song-editor will provide the writer with a better feel of where the text is in relation to the actual song; as opposed to writing all annotations in a separate window.

#### Mockup

Notes (or Annotation?) tracks can be added to the song-editor and look similar to any other type of track (only with no mute button obviously.) The bars present a small snippet of the text they contain (similar to the sample tracks showing the file-name.)
Hovering over (or double-clicking?) a notes bar will open a mini text-editor interface to see and edit the full text.

Start by locating the song-editor and Project Notes implementations described in the issue, then compare how instrument tracks represent bars and editing interactions. Define the annotation-track behavior, text editing workflow, and relationship to Project Notes before implementing; done means notes can be positioned with song bars, viewed and edited, and do not produce audio.

Written by the indexing model from the issue text.