OtonH8ing-py/StemForge-StemSeparator-ytdownloader-scldownloader-sampler-editor — reverse-engineered prompt

Build me a local desktop app called StemForge for Windows that feels like an all in one music toolkit. I want to be able to download permitted audio from YouTube and SoundCloud, convert it, play it back, and keep a simple workspace library of my tracks. It should analyze songs for BPM, musical key, and Camelot, then let me open a track editor with a colored waveform, zoom, in and out points, volume control, and live BPM and key preview while the track is playing. When I export a cut, it should keep the BPM and key settings I chose.

I also want stem separation with both Demucs and MDX style models, plus a stem mixer where I can mute, solo, change volumes, save presets, send stems to the editor, and export a mix. If a stem engine or model is missing, show that clearly instead of breaking.

Please make it runnable from source and also easy to package as a portable Windows build or installer. Use legal download rules, and look up current docs online if you need to.