Reorganize docker-compose stacks for better service grouping

Stack changes:
- Renamed media-extended.yml → media-management.yml (better clarity)
- Moved Plex from media → alternatives (Jellyfin is primary)
- Moved code-server from utilities → infrastructure
- Moved Sonarr, Radarr, Prowlarr from media → media-management
- Moved Calibre-web from media-management → media

New stack organization:
- media.yml (3): Jellyfin, Calibre-web, qBittorrent
- media-management.yml (13): All *arr apps, transcoders
- alternatives.yml (6): Plex, Portainer, Authentik
- infrastructure.yml (7): Added code-server
- utilities.yml (6): Removed code-server

Documentation updated:
- README.md: Updated stack descriptions
- services-overview.md: Updated service counts and locations
- All service docs: Updated file paths media-extended → media-management

docs/service-docs/unmanic.md

@@ -75,7 +75,7 @@ Library Optimized
 ### Directory Structure
 
 ```
-/opt/stacks/media-extended/unmanic/config/    # Configuration
+/opt/stacks/media-management/unmanic/config/    # Configuration
 /mnt/media/movies/                            # Movie library
 /mnt/media/tv/                               # TV library
 /tmp/unmanic/                                # Temp files
@@ -135,7 +135,7 @@ unmanic:
     - PGID=1000
     - TZ=America/New_York
   volumes:
-    - /opt/stacks/media-extended/unmanic/config:/config
+    - /opt/stacks/media-management/unmanic/config:/config
     - /mnt/media:/library
     - /tmp/unmanic:/tmp/unmanic
   devices: