Fix VRAM property access in training script to use total_memory

code/train_production.py

@@ -436,7 +436,7 @@ def train(args):
     print(f"Device: {device}")
     if torch.cuda.is_available():
         print(f"GPU: {torch.cuda.get_device_name()}")
-        print(f"VRAM: {torch.cuda.get_device_properties(0).total_mem / 1e9:.1f} GB")
+        print(f"VRAM: {torch.cuda.get_device_properties(0).total_memory / 1e9:.1f} GB")
     
     # Download dLLM model
     print("Downloading dLLM Qwen3-0.6B diffusion model...")