Fix CORS and API URLs for container communication

docker-compose-frontend.yml

@@ -32,6 +32,7 @@ services:
       CONFIG_DIR: /config
       LISTEN_ADDR: "0.0.0.0:${WIZARD_PORT:-8080}"
       MAX_BACKUPS: "5"
+      # Internal network only
       CORS_ORIGINS: http://frontend:${FRONTEND_PORT:-3000}
     ports:
       - "127.0.0.1:${WIZARD_PORT:-8080}:${WIZARD_PORT:-8080}"
@@ -67,6 +68,7 @@ services:
     container_name: harborforge-test-frontend
     restart: "no"
     environment:
+      # Use internal service name
       VITE_API_BASE_URL: http://backend:${BACKEND_PORT:-8000}
     networks:
       - test-network