Fix: scroll track textures at the same rate

Dragging a tank's track scrolled its roughness/metalness texture at twice the speed of the base color and normal textures, so highlights drifted off the track links.

**Cause**
- `translateTexture` added the scroll offset to `roughnessMap` and `metalnessMap` separately
- glTF has a single metallic-roughness texture, and the loader assigns that same texture object to both slots, so it received the offset twice

**Changes**
- Collect the track's maps in a `Set` before scrolling so a texture shared between slots is offset exactly once

packages/website/src/components/Tankopedia/HeroSection/components/TankSandbox/components/TankModel.tsx

@@ -51,11 +51,17 @@ export function TankModel() {
 
           invalidate();
 
-          if (material.map) material.map.offset.y += offset;
-          if (material.aoMap) material.aoMap.offset.y += offset;
-          if (material.normalMap) material.normalMap.offset.y += offset;
-          if (material.roughnessMap) material.roughnessMap.offset.y += offset;
-          if (material.metalnessMap) material.metalnessMap.offset.y += offset;
+          const textures = new Set([
+            material.map,
+            material.aoMap,
+            material.normalMap,
+            material.roughnessMap,
+            material.metalnessMap,
+          ]);
+
+          for (const texture of textures) {
+            if (texture) texture.offset.y += offset;
+          }
         }
 
         function onPointerDown(event: ThreeEvent<PointerEvent>) {