[fix] move PyMCubes output tensors to input device

PyMCubes returns numpy arrays (CPU). Need to move the resulting
torch tensors back to the original device (cuda:0) to match
the rest of the model's tensors.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tsr/models/isosurface.py

@@ -41,10 +41,11 @@ class MarchingCubeHelper(IsosurfaceHelper):
         self,
         level: torch.FloatTensor,
     ) -> Tuple[torch.FloatTensor, torch.LongTensor]:
+        device = level.device
         level = -level.view(self.resolution, self.resolution, self.resolution)
         v_pos, t_pos_idx = self.mc_func(level.detach().cpu().numpy(), 0.0)
-        v_pos = torch.from_numpy(v_pos.astype(np.float32))
-        t_pos_idx = torch.from_numpy(t_pos_idx.astype(np.int64))
+        v_pos = torch.from_numpy(v_pos.astype(np.float32)).to(device)
+        t_pos_idx = torch.from_numpy(t_pos_idx.astype(np.int64)).to(device)
         v_pos = v_pos[..., [2, 1, 0]]
         v_pos = v_pos / (self.resolution - 1.0)
         return v_pos, t_pos_idx