Arn Infra Env

- This skill should be used when the user says "manage environments", "arn infra env", "infra env", "environment setup", "configure environments", "set up staging", "set up production", "environment management", "create environment", "environment promotion", "promote to staging", "promote to production", "environment isolation", "configure dev staging prod", "environment-specific config", "tfvars per environment", "arn-infra-env", or wants to configure, create, or manage infrastructure environments (dev/staging/production) with isolation strategies, variable overrides, and promotion rules.