Add the typed/named convenience view on `WalkForwardResult`, closing the
symmetry cycle 0048 left open: it shares the `(space, tag-free Vec<Cell>)`
idiom with `SweepFamily` but had no named-params accessor, so a consumer
hand-wrote `zip_params(&result.space, &result.windows[i].run.chosen_params)`.
`named_params(window)` pairs each param-space name with that window's chosen
value in slot order, delegating to `zip_params` — the direct mirror of
`SweepFamily::named_params`. A derived view, no new stored state.
closes#76
Brummel
8b22fa6c73