Add promo directory to gitignore

Add piano sound, play modes, and free play keyboard mode

Sync all READMEs to 29 verified songs

Verify all songs from real MIDI, remove unverified ones

Fix Chopin Ballade No.1: replace bad MIDI source with accurate version

Fix MIDI extraction: preserve fast note runs, replace wrong Fur Elise MIDI

Update all READMEs to reflect current state

Replace piano samples with Electric Piano (Rhodes) from GM SoundFont

Remove octave filtering from MIDI conversion, include full range

Replace synthesized samples with real piano recordings

Fix song data: extract from real MIDI files instead of AI approximation

Add 15 popular songs, fix all melodies to be melody-only

Initial release: terminal typing piano with 20 classical pieces

Initial commit