Interface MlxForwardStep

One forward a method hands to the mixed iteration: the phase its rows run in, their count and width class, the drafter's capture, and the forward those rows run on their own, which the iteration calls when it does not pack them with another group.

interface MlxForwardStep {
    capture: MlxLayerCapture | null;
    phase: "window" | "decode" | "verify";
    rows: number;
    own(): Promise<MlxArray>;
}