Use solo piano optimizer for full-song melodic stem, reduce LH bass notes

Fix MetalSynth API (HH/ride/crash) and use mix audio for beat tracking

Fix piano roll quality, drum sounds, add original audio playback, fix speed

Add drum transcription with madmom onset detection + spectral classification

Fix bass in piano roll, upgrade guitar samples, improve bass optimizer

Remove unused vocal transcription and arrangement from full song pipeline

Use direct melodic transcription for piano roll instead of arrangement

Improve transcription quality + upgrade to Magenta SGM+ samples

Sample-based guitar/bass sounds, filter bass from piano roll, two guitar tabs

Full Song quality pass: light optimizer, better guitar sound, tab accuracy

Add piano arrangement engine + guitar/bass tab views for Full Song mode

Add Full Song mode with Demucs source separation

Initial commit - Mr Octopus piano tutorial app