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.

agent/pyproject.toml

@@ -16,7 +16,6 @@ dependencies = [
     "livekit-plugins-openai~=1.7",
     "python-dotenv",
     "uvicorn>=0.52.4",
-    "yt-dlp>=2026.8.19",
 ]
 
 [tool.setuptools.packages.find]