feat: extract opengait_studio monorepo module

Move demo implementation into opengait_studio, retire Sports2D runtime integration, and align packaging with root-level monorepo dependency management.

opengait/modeling/modules.py

@@ -2,7 +2,7 @@ import torch
 import numpy as np
 import torch.nn as nn
 import torch.nn.functional as F
-from utils import clones, is_list_or_tuple
+from opengait.utils import clones, is_list_or_tuple
 from torchvision.ops import RoIAlign