Normalizes .exs workflow files to workflow documents.

An .exs workflow is an Elixir script whose final expression evaluates to a map describing the workflow. This is a low-level generation escape hatch. Human-authored workflow files should generally use HCL and let Condukt.Workflows.HCLCompiler produce the same map.

Atom keys and atom values (other than nil, true, false) are normalized to strings; the rest of the data must already match the workflow document shape.

Standard Elixir features (def inside a defmodule, anonymous functions, for, if, comprehensions, Enum, etc.) are available for document generation. References between steps are written as plain ${...} expression strings.

# hello.exs
%{
  inputs: %{name: %{type: :string}},
  steps: %{greet: %{kind: :cmd, argv: ["echo", "Hello, ${inputs.name}"]}},
  output: "${steps.greet.stdout}"
}