Stateless HTTP transport — Req against the Dust REST API. Suitable
for one-shot scripts, release tasks, and contexts where the WS
supervisor isn't running. No realtime: subscribe/3 returns
{:error, :not_supported}.
All bodies are encoded/decoded with the stdlib JSON module
(Elixir 1.18+). The token comes from config :dustlayer_ecto, :token;
base URL from :base_url.