feat(ui): ui_scale and ui_box, on-submit, zoom (and a length over a length in calc), on-hold

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.ui/node_more.ludic

@@ -29,6 +29,7 @@ export property UiNodeX {
   grad: UiGradient = null       # background: linear-gradient(...)
   ratio: float = 0.0            # aspect-ratio, width over height; 0 none
   fit_obj: int = 0              # object-fit: 0 fill, 1 contain, 2 cover, 3 none, 4 scale-down
+  zoom: float = 1.0             # zoom: this element and everything inside it, larger or smaller
 }
 function nx(n: UiNode) -> UiNodeX {
   if n.ex == null { n.ex = new UiNodeX }