Pure config and mode helpers for the Codex ACP adapter.
@spec default_mode() :: String.t()
@spec default_reasoning_effort() :: String.t()
@spec merge_mode_wire_params(map(), String.t() | nil) :: map()
@spec mode_id_from_result(map()) :: String.t() | nil
@spec modes() :: [map()]
@spec normalize_mode_id(any()) :: String.t()
@spec normalize_requested_mode(any()) :: {:ok, String.t()} | {:error, String.t()}
@spec reasoning_efforts() :: [{String.t(), String.t()}]