fix(editor): guard null bounds in box-select registry-selectable branch (#359)

The registry-driven selectable branch in `collectNodeIdsInBounds` called
`objectBoundsIntersectsBounds(node.id, bounds)` directly, but `bounds` is
`Bounds | null` (null = select-all / no rectangle). Every other branch
guards with `!bounds ||`; this one didn't, so `tsc --build` failed in
consumers (`@pascal-app/nodes`) with TS2345 "Bounds | null not assignable
to Bounds". Add the same guard, which also restores correct select-all
behavior for registry-selectable kinds.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

packages/editor/src/components/tools/select/box-select-tool.tsx

@@ -285,7 +285,7 @@ function collectNodeIdsInBounds(bounds: Bounds | null): string[] {
         // Registry-driven selectable kinds (shelf + future furnish/structure
         // kinds) aren't in the hardcoded list above; pick them up by their
         // rendered bounding box, the same path column/stair use.
-        if (objectBoundsIntersectsBounds(node.id, bounds)) {
+        if (!bounds || objectBoundsIntersectsBounds(node.id, bounds)) {
           result.push(node.id)
         }
       }