cf53912a33
Issue: #9 Backend: - GET /api/list-wavs?dir=<path> — lists .wav files in a directory - GET /wavs/<file> — static file serving from ./output/wavs Web UI: - WAV Browser section with path input + Browse button - AudioContext-based playback (zero deps) — progress bar, time display - WAV file grid with Play buttons, active item highlighting Tests: - 3 new tests for handleListWavs (wav files, empty dir, nonexistent dir) - Fix TestFindAkaiutil: add t.Chdir(tmp) so relative path lookups don't accidentally find the repo's third_party/akaiutil/akaiutil binary