/api/sounds (admin) takes the raw file, converts it with ffmpeg in one
pass to <id>.wav (8 kHz) and <id>.g722 (HD for G.722 calls) in SOUNDS_DIR,
measures it with ffprobe, and stores it as custom/<id>. Delete answers 409
with what still plays it (IVR greeting/invalid sound, announcements, the
recording notice). Sounds & music page: drop or pick a file (name
suggested from the file name), play, rename, delete. MOH classes stay in
M8. The web client and greetings share one raw-upload helper; the
api test audio helpers moved to test/audio.ts.
e2e m6-t1: drag-and-drop upload in the browser, Asterisk plays
custom/<id>, rename, delete refused while in use, then deleted.
Task: M6-T1
iamdoubz