Refine .env.example files across all stacks

- Streamline variable organization and formatting
- Reduce redundant comments and improve clarity
- Maintain all required variables for each stack

docker-compose/productivity/.env.example

@@ -1,27 +1,21 @@
 # Productivity Stack Environment Variables
-# These variables are used for productivity and collaboration tools
 
-# Base Configuration
-DOMAIN=
 TZ=
-
-# User Configuration
 PUID=
 PGID=
+SERVER_IP=
+SERVER_HOSTNAME=
+DOMAIN=
 
-# Nextcloud Configuration
 NEXTCLOUD_DIR=
 NEXTCLOUD_ADMIN_USER=
 NEXTCLOUD_ADMIN_PASSWORD=
 NEXTCLOUD_DB_PASSWORD=
 NEXTCLOUD_DB_ROOT_PASSWORD=
 
-# WordPress Configuration
 WORDPRESS_DB_PASSWORD=
 WORDPRESS_DB_ROOT_PASSWORD=
 
-# Gitea Configuration
 GITEA_DB_PASSWORD=
 
-# Jupyter Configuration
 JUPYTER_TOKEN=