mojs/mojs-timeline-editor — reverse-engineered prompt

Build me a simple browser based timeline editor for mojs animations. I want something I can open locally while I’m crafting an animation, where I can preview it live, scrub through the timeline, play and pause it, and visually tweak timing instead of guessing numbers by hand. It should help with editing HTML based animation pieces, custom points, and the overall timeline in a clear GUI.

Please make it feel like a small creative tool, not just a demo. If it makes sense, let me adjust values with direct controls, see changes instantly, and export or copy the updated animation code so I can use it in my project. Since this package is not published yet, set it up so it runs in a local dev server and works with mojs loaded first. Keep the setup straightforward, and if the README is thin in places, look up current mojs docs online and make reasonable choices that match the project goal.