/api/me/voicemail lists, streams (Range, download) and marks read or
deletes through AMI VoicemailMove/VoicemailRemove, then rescans so MWI
and the list agree. /api/me/greetings takes the raw recording or file and
converts it with ffmpeg to 8 kHz PCM (media/audio.ts). My Phone gets a
layout with Home (new voicemails) and Voicemail (play marks read,
download, delete, record/upload greetings via MediaRecorder); the list
refetches on the live voicemail.new event. e2e m4-t3 checks MWI goes off
within 5 s after play and delete, and a browser-recorded greeting is what
callers hear.
Task: M4-T3
