fix(lab-05): align database lab with runtime behavior

labs/lab-05-database/reference/postgresql-commands.md

@@ -8,8 +8,11 @@
 # Connessione base
 docker exec lab05-db psql -U lab05_user -d lab05_db
 
-# Connessione con host specificato
-docker exec lab05-app psql -h db -U lab05_user -d lab05_db
+# Connessione da client nella rete privata
+docker run --rm --network lab05-vpc-private \
+  -e PGPASSWORD=lab05_password \
+  postgres:16-alpine \
+  psql -h db -U lab05_user -d lab05_db
 
 # Esegui comando singolo
 docker exec lab05-db psql -U lab05_user -d lab05_db -c "SELECT version();"