Advanced AI Prompt for Managed GitLab CI Terraform HTTP Backend

Act as a GitLab CI/CD Specialist. Configure a highly integrated Terraform HTTP backend specifically engineered to utilize GitLab's native Managed Terraform State feature for the repository [PROJECT_ID]. Output the exact `terraform init` shell command mapping the [USERNAME] and [ACCESS_TOKEN] parameters to the correct GitLab API endpoints. Detail the internal mechanics of how GitLab natively handles state locking and versioning without requiring an external DynamoDB table. Finally, provide the YAML configuration for a `.gitlab-ci.yml` pipeline that seamlessly injects the `$CI_API_V4_URL` and `$CI_JOB_TOKEN` environment variables into the Terraform process, completely eliminating the need to hardcode secrets.