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.

nginx.conf

@@ -22,27 +22,6 @@ server {
         proxy_read_timeout 3600s;
         proxy_send_timeout 3600s;
     }
-
-    # Media server API (library, search, player state) and the proxy for
-    # external live-stream URLs (http:// sources would be blocked as mixed
-    # content in the browser, so they are re-served over HTTPS from here).
-    location /media/api/ {
-        proxy_pass http://127.0.0.1:8093/media/api/;
-        proxy_buffering off;
-        proxy_read_timeout 3600s;
-        proxy_send_timeout 3600s;
-    }
-
-    # Downloaded tracks are plain static files — nginx serves them with
-    # native HTTP Range support, which gives the web player seeking for free.
-    location /media/files/ {
-        alias /data/media/files/;
-    }
-
-    location /media/thumbs/ {
-        alias /data/media/thumbs/;
-    }
-
     location / {
         try_files $uri $uri/ =404;
     }