Prod: public origin gupi.glitch.university, internal services over HTTP

CORS_ORIGIN defaults to https://gupi.${DOMAIN} (the TLS frontend served by the
proxy); the app still reaches Postgres/MinIO by their docker hostnames over
plain HTTP on the shared network. Clarify the split in .env.prod.example and
fix the deploy success URL.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

deploy.sh

@@ -98,4 +98,4 @@ for i in $(seq 1 24); do
   fi
 done
 
-echo "==> Done! https://osint.glitch.university"
+echo "==> Done! https://gupi.glitch.university"