fix(strixhalo): add re-entry guard to prevent offload-arch fork bomb

torch init calls offload-arch (a Python script) which re-enters the
.pth hook, triggering another import torch, creating an infinite fork
storm (1000+ processes). Set _STRIXHALO_VRAM_FIX_ACTIVE env var before
importing torch so child processes skip the patch.

amdsmi-shim/strixhalo_vram_fix.py

@@ -55,8 +55,17 @@ def _get_real_vram() -> tuple[int, int] | None:
     return None
 
 
+_GUARD_ENV = "_STRIXHALO_VRAM_FIX_ACTIVE"
+
+
 def _should_skip() -> bool:
-    """Check if we should skip the patch (lightweight/init containers)."""
+    """Check if we should skip the patch (re-entry guard, init containers)."""
+    # Re-entry guard: importing torch triggers subprocess calls to
+    # offload-arch (a Python script), which re-enters this .pth hook.
+    # Without this guard it creates an infinite fork bomb.
+    if os.environ.get(_GUARD_ENV):
+        return True
+
     # Check cgroup memory limit — if under 512Mi, skip the expensive
     # torch/ROCm import. KubeRay's wait-gcs-ready init container has
     # only 256Mi and importing torch+ROCm would OOMKill it.
@@ -82,6 +91,10 @@ def _apply_patch() -> None:
     if _get_real_vram() is None:
         return
 
+    # Set guard BEFORE importing torch — torch init spawns offload-arch
+    # (a Python script) which would re-enter this .pth hook without it.
+    os.environ[_GUARD_ENV] = "1"
+
     try:
         import torch
         if not hasattr(torch, "cuda") or not torch.cuda.is_available():