Add robust PyTorch pytree compatibility shim

Create bidirectional aliases for _register_pytree_node/register_pytree_node
to support both older and newer PyTorch versions with AudioCraft.

The API changed between versions - older uses underscore prefix (private),
newer uses no prefix (public). This shim creates both aliases.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

main.py

@@ -16,6 +16,20 @@ os.chdir(PROJECT_ROOT)
 # Add project root to path
 sys.path.insert(0, str(PROJECT_ROOT))
 
+# PyTorch pytree compatibility shim for AudioCraft
+# The API changed between PyTorch versions:
+#   - Older: _register_pytree_node (private, with underscore)
+#   - Newer: register_pytree_node (public, without underscore)
+# Create aliases in both directions to support any version
+try:
+    import torch.utils._pytree as _pytree
+    if hasattr(_pytree, '_register_pytree_node') and not hasattr(_pytree, 'register_pytree_node'):
+        _pytree.register_pytree_node = _pytree._register_pytree_node
+    if hasattr(_pytree, 'register_pytree_node') and not hasattr(_pytree, '_register_pytree_node'):
+        _pytree._register_pytree_node = _pytree.register_pytree_node
+except Exception:
+    pass  # Ignore if torch not installed or patch fails
+
 from config.settings import get_settings
 from src.core.gpu_manager import GPUMemoryManager
 from src.core.model_registry import ModelRegistry