musescore/MuseScore ? reverse-engineered prompt

Build me a free music notation and composition app in the spirit of MuseScore Studio. I want a desktop program where someone can write sheet music on a virtual page, enter notes quickly, edit them easily, and hear the score played back with a built in sequencer and software synth.

It should support importing and exporting common score formats like MusicXML, MIDI, and MEI, plus MuseData import. It should also let people use MIDI input to enter notes, and print the finished score or save it as a PDF. The editing experience should feel WYSIWYG, so what you see while writing is basically what gets printed.

Please wire up the project so it builds and runs cleanly from the repo, include whatever setup is needed for the submodules and tests, and leave simple run instructions so I can open it and try it right away. If anything is unclear, look up the current project docs online and follow the recommended build path.