refactor: split music streaming into Hope Music

Move the media server, downloader, library volume, and browser player to the
standalone hope-media-music product. Keep Hope's music tools as a thin HTTP
client of the LAN service on port 8094.

Use a stable voice-room player scope instead of ephemeral LiveKit room names.
The agent now owns the conversation handshake: fresh reported playback mutes
its input, joining pauses music, and the last participant leaving resumes only
music it paused. Peer failures remain non-fatal.

Also move the voice deploy workflow onto the active Unraid Gitea runner and
remove yt-dlp/ffmpeg/media health and volume dependencies from the image.

web/token_server.py

@@ -97,8 +97,8 @@ class Handler(BaseHTTPRequestHandler):
         resp = json.dumps(
             {
                 "token": token,
-                # The room name scopes media-server player state; the UI sends
-                # it with every /media/api/ call.
+                # Returned for diagnostics and reconnects. Music deliberately
+                # uses its own stable scope in the separate Hope Music service.
                 "room": room_name,
                 "user": {
                     "id": user_id,