Audio-to-MIDI transcription (basic-pitch) — present in old slopsmith-plugin-editor, missing here

[carochacs]

Migrated from: got-feedBack/feedBack-plugin-editor#361

The old slopsmith editor had audio-to-MIDI transcription via basic-pitch. This feature was present but has been dropped in the current feedBack editor.

Restoring this would allow users to transcribe melodies or bass lines directly from audio, significantly speeding up chart creation workflow.

See original issue for technical approach (basic-pitch library) and integration points.