fix: IS 4.1.0 + Blackwell GPU compatibility fixes

- Add scipy Rotation scalar_first monkey-patch for older scipy (<1.11)
- Fix SimulationApp import to support both IS 4.x and 5.x
- Reuse task object across reset() calls to prevent duplicate prims
- Add _scene_initialized guard in set_up_scene() for repeated resets
- Cache arena_file_path to survive task_cfg.pop()
- Clean up collision groups before re-creating
- Switch to PathTracing renderer for clean output on Blackwell GPU

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

launcher.py

@@ -5,6 +5,41 @@ from nimbus.utils.utils import init_env
 
 init_env()
 
+# Patch scipy.spatial.transform module so that `from_quat` and `as_quat`
+# accept `scalar_first=` on older scipy (< 1.11).
+try:
+    from scipy.spatial.transform import Rotation as _R
+    _R.from_quat([1, 0, 0, 0], scalar_first=True)
+except TypeError:
+    import numpy as _np
+    import scipy.spatial.transform as _sst
+    from scipy.spatial.transform import Rotation as _OrigR
+
+    class Rotation(_OrigR):
+        @classmethod
+        def from_quat(cls, quat, *args, scalar_first=False, **kwargs):
+            quat = _np.asarray(quat, dtype=float)
+            if scalar_first:
+                if quat.ndim == 1:
+                    quat = _np.array([quat[1], quat[2], quat[3], quat[0]])
+                else:
+                    quat = _np.concatenate([quat[..., 1:], quat[..., :1]], axis=-1)
+            return super().from_quat(quat, *args, **kwargs)
+
+        def as_quat(self, *args, scalar_first=False, **kwargs):
+            q = super().as_quat(*args, **kwargs)
+            if scalar_first:
+                if q.ndim == 1:
+                    q = _np.array([q[3], q[0], q[1], q[2]])
+                else:
+                    q = _np.concatenate([q[..., 3:], q[..., :3]], axis=-1)
+            return q
+
+    _sst.Rotation = Rotation
+    import sys
+    sys.modules['scipy.spatial.transform._rotation'].Rotation = Rotation
+    sys.modules['scipy.spatial.transform'].Rotation = Rotation
+
 import argparse
 
 from nimbus import run_data_engine