Add v1.1 GPU-trained ResNet50 baseline

[rhouhou]

Summary

This PR adds the v1.1 GPU-trained ResNet50 baseline.

Updates

• Added Colab GPU training configuration
• Updated test metrics using a GPU-trained ResNet50 model
• Updated ROC and PR curves
• Updated confusion matrix
• Updated Grad-CAM examples
• Updated README and MODEL_CARD with v1.1 results

Results

Model	Accuracy	ROC-AUC	PR-AUC	Brier Score
ResNet50 GPU baseline	0.902	0.971	0.975	0.078

Notes

The dataset, PyTorch checkpoint, and ONNX model are not included in the repository.