Fix admin authentication and update port mapping

- Fix environment variable mismatch in create_default_user.py
- Now correctly uses ADMIN_USER and ADMIN_PASSWORD from docker-compose
- Maintains backward compatibility with DEFAULT_USER and DEFAULT_PASSWORD
- Change port mapping from 8880 to 80 for easier access
- Resolves login issues with admin user credentials

docker-compose.yml

@@ -8,7 +8,7 @@ services:
     image: digiserver:latest
     container_name: digiserver
     ports:
-      - "8880:5000"
+      - "80:5000"
     environment:
       - FLASK_APP=app.py
       - FLASK_RUN_HOST=0.0.0.0