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/core/.env.example

@@ -1,25 +1,17 @@
 # Core Stack Environment Variables
-# These variables are used for Traefik, Authelia, DuckDNS, and Pi-hole
 
-# Base Configuration
-DOMAIN=
 TZ=
-
-# Server Configuration
-SERVER_IP=
-
-# User Configuration
 PUID=
 PGID=
+SERVER_IP=
+SERVER_HOSTNAME=
+DOMAIN=
 
-# DuckDNS Configuration
 DUCKDNS_SUBDOMAINS=
 DUCKDNS_TOKEN=
 
-# Pi-hole Configuration
 PIHOLE_PASSWORD=
 
-# Authelia Configuration (Generated by script)
 AUTHELIA_JWT_SECRET=
 AUTHELIA_SESSION_SECRET=
 AUTHELIA_STORAGE_ENCRYPTION_KEY=