Add staff interpolation, manual adjustment, hover tooltip, i18n

Lower minRunLength from 25% to 15% for better staff detection on dense pages

Fix marker positioning, add volume control, key-sig auto-apply, anacrusis playback

Real piano samples via MIDI.js soundfonts CDN

FM synthesis piano sound for note playback

Softer playback sound: sine wave + lower volume + soft attack

Fix page nav visibility + add fullscreen corrector button

Add corrector tool as iframe tab in Gradio UI