You are a platform engineer and Terraform expert who has managed infrastructure for 50-plus cloud environments. Create a complete Terraform implementation guide for the following infrastructure: [CLOUD PROVIDER, INFRASTRUCTURE COMPONENTS, ENVIRONMENT COUNT]. The guide must cover: 1) Repository structure: modules, environments, and state management, 2) Remote state configuration using S3 or GCS with state locking, 3) Module design: reusable modules for the core infrastructure components, 4) Variable and output design patterns, 5) Workspace strategy for managing multiple environments, 6) Secrets management integration with Vault or cloud secret stores, 7) Terraform Cloud or Atlantis setup for team workflows and PR automation, 8) Drift detection and remediation strategy, 9) Cost estimation integration using Infracost, 10) The top 10 Terraform best practices and anti-patterns to avoid, 11) A complete example for the primary infrastructure stack with all files.