floor-elevation: restore stripped import + fix column rotation type

Two follow-up fixes after the FloorElevationSystem landed:

 - `viewer/src/components/viewer/index.tsx`: the auto-format hook
   stripped the `FloorElevationSystem` import a second time, leaving
   the JSX mount unresolved.
 - `packages/nodes/src/column/definition.ts`: column stores Y rotation
   as a scalar `number`, but `floorPlaced.footprint` types the rotation
   field as the full Euler tuple. Wrap as `[0, column.rotation, 0]`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/nodes/src/column/definition.ts

@@ -44,7 +44,9 @@ export const columnDefinition: NodeDefinition<typeof ColumnNode> = {
         const column = node as ColumnNodeType
         return {
           dimensions: [column.width, column.height, column.depth] as [number, number, number],
-          rotation: column.rotation,
+          // Column stores Y rotation as a scalar; the slab-overlap query
+          // expects the full Euler tuple.
+          rotation: [0, column.rotation, 0] as [number, number, number],
         }
       },
     },