Inventory: centre the rotating phone model in the rack

Its geometry hangs below the hinge pivot, so it sat low; lift it so the
handset is vertically centred in the tool carousel.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/inventory.tsx

@@ -12,7 +12,7 @@ function buildPhoneModel() {
   const { group, hinge } = buildPhone()
   hinge.rotation.x = CLOSED_ANGLE // sit closed on the rack
   group.scale.setScalar(1.15)
-  group.position.y = -0.05
+  group.position.y = 0.5 // the phone's mass hangs below its pivot — lift it to centre in frame
   return group
 }