swordalt/dancerail3-editor — reverse-engineered prompt

Build me a browser based fan made chart editor for DanceRail3, similar to DR3Maker. I want to be able to load or create charts in the official format, place and edit notes, change note properties, organize note IDs, and use undo and redo while editing.

Please include an eased note generator that also works for hold notes, plus live chart stats so I can see useful info while working. Add a top down preview of the chart that can show things like SC, NSC, note appear mode, camera tilt, and camera movement. I also want export options for the raw chart data and a DR3FV style export with an info.txt file.

Make the UI practical for charting, with keyboard shortcuts and a help button that shows the keybinds. Use the existing hit and flick sounds where they make sense. Keep it simple but usable, and look up current docs online if you need to.