Docker / CI: Hardcoded API URL prevents multi-environment setup

[francescobianco]

Labels: config, ci, docker
Context: Docker-based deployments and GitHub Actions CI

Description:
The base API URL is hardcoded in the SDK. Developers cannot override it through environment variables in Docker or CI/CD pipelines.

Expected:
Openapi::configure(['base_url' => getenv('OPENAPI_URL')]);

Impact:
Cannot properly separate test, staging, and production environments in automated workflows.