Add 3d control buttons to linear mode (#8178)

Adds control buttons to the top left of the 3d preview in linear mode.
<img width="460" alt="image"
src="https://github.com/user-attachments/assets/35a83b9c-65af-46c3-a910-be5ad30c428e"
/>


This was deprioritized because I forgot the secret to magically
unwrapping a set of refs (wrap them in another ref).

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8178-Add-3d-control-buttons-to-linear-mode-2ee6d73d3650816ab1a8e73ace1bdbc7)
by [Unito](https://www.unito.io)

src/composables/useLoad3dViewer.ts

@@ -630,6 +630,10 @@ export const useLoad3dViewer = (node?: LGraphNode) => {
     handleBackgroundImageUpdate,
     handleModelDrop,
     handleSeek,
-    cleanup
+    cleanup,
+
+    hasSkeleton: false,
+    intensity: lightIntensity,
+    showSkeleton: false
   }
 }