Advanced AI Prompt for Terraform GitOps CI/CD Directory Structure

Act as a Lead Infrastructure-as-Code Developer. Architect an enterprise-grade, highly scalable Terraform directory structure explicitly designed to integrate flawlessly with a strict GitOps CI/CD pipeline. You must map out the absolute folder hierarchy required to manage a [MULTI_ENV_SETUP] (e.g., dev, staging, prod) across multiple [CLOUD_PROVIDER] accounts. Definitively solve the code-duplication problem by demonstrating exactly how to abstract core infrastructure into a centralized [MODULE_REGISTRY]. Provide a rigorous technical explanation detailing why the 'Terragrunt' wrapper pattern or Terraform Workspaces should be used to inject environment-specific variables, mathematically ensuring that a commit to 'staging' can never accidentally mutate the 'production' state file.