Pipeline runner: dotted access into a forEach item ($param:"item.field") (child of #94) #114

Gap found by the #94 capstone ("GAP #2" in lead-finder.test.ts).

Problem. resolveInputValue exposes the current forEach item ONLY as the whole object via {$param:"item"}. There is no way to read a field of it — {$param:"item.lat"} falls through to scope.params["item.lat"] (undefined). So a forEach body can't plug item.lat/item.lng into a Places request body, nor item.websiteUri into an http_reachable url.

Evidence. resolveInputValue({$param:"item.lat"}, {…, item:{lat:-33.9}}) → undefined (asserted). {$param:"item"} → the whole {lat:…} works.

Consequence. Blocks BOTH per-cell grid search (needs item.lat/item.lng in the request body) and per-record reachability (needs item.websiteUri).

Proposed fix. In resolveInputValue, when obj.$param starts with item. and scope.item !== undefined, read the dotted remainder off scope.item (reuse the existing readPath). i.e. $param:"item" → whole item; $param:"item.lat" → readPath(scope.item,"lat"). One-line-ish, backward compatible.

Part of #94.