Simplify nested ternary operator for environment variable

[coderabbitai]

The current implementation of the env variable uses a nested ternary operator, which can be complex and hard to read. To improve readability and maintainability, consider using a map-based approach.

Example Solution:

locals {
  env_map = {
    "sandbox"        = "sb"
    "non-production" = "non-prod"
    "production"     = "prod"
  }

  env = lookup(local.env_map, var.environment, "none")
}

This approach avoids nested ternary operators and makes it easier to extend in the future.

[brettcurtis]

Fixed in #7