Opaque, request-scoped information supplied by a transport.
Protocol-independent code should not infer transport policy from this struct.
@type headers() :: %{optional(String.t()) => String.t()} | [{String.t(), String.t()}]
@type t() :: %Snodo.Transport.Context{ connection_ref: term(), metadata: map(), peer: term(), request_headers: headers(), response_handle: term(), transport: atom() | module() | nil }