extract.go replaces the bash script with idiomatic Go:
- akaiutil process communication via stdin/stdout pipes
- partition enumeration (df output parsing)
- volume enumeration (dir output parsing per partition)
- sample2wavall per volume with WAV count aggregation
runAkaiutil is a package-level var — tests stub it with canned
output to verify parsing without a real akaiutil binary or ISO.
Removed: findScript(), -tool flag on extract, os/exec from main.go
Kept: extract_wavs.sh as a standalone utility (no longer called)
