RouterClient implementation that calls POST /v1/route over HTTP via Req.
Options
:base_url(required) — e.g."https://gateway.example.com".:bearer_token(required) — the caller's bearer token.:plug(optional) — a plug (module or function) handling the request in-process instead of a live HTTP call — theReq.Testseam; used by this library's own tests and smoke task.
Response normalization
The JSON response (string keys) is parsed into a %Mimir.RouteResponse{} by
Mimir.RouteResponse.new/1 — the single struct boundary; this client
performs no key atomization of its own.