notepat: drum mode swaps only upper octave, add trigger logs
Previously drumMode converted every note (both octaves) to the 12-drum
kit, which didn't match the native kitRight semantics and made it feel
like the button wasn't doing anything — you lost your melody row too.
Now drumMode only intercepts notes prefixed with "+" / "++" (the upper
grid), so the lower octave keeps pitched playback and you can play
melody + drums at once. Added 🥁 console logs on toggle and on each
drum hit so the route is visible while debugging.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>