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/calibre-web.md

@@ -49,7 +49,7 @@ Calibre-Web is a web-based ebook reader and library manager. It provides a clean
 ### Directory Structure
 
 ```
-/opt/stacks/media-extended/calibre-web/config/    # Config
+/opt/stacks/media-management/calibre-web/config/    # Config
 /mnt/media/books/                                 # Calibre library
 ```
 
@@ -84,7 +84,7 @@ calibre-web:
     - TZ=America/New_York
     - DOCKER_MODS=linuxserver/mods:universal-calibre
   volumes:
-    - /opt/stacks/media-extended/calibre-web/config:/config
+    - /opt/stacks/media-management/calibre-web/config:/config
     - /mnt/media/books:/books
   labels:
     - "traefik.enable=true"