Add GPU Handling in neural network Model Base Class

[benlyazid]

Currently, GPU usage is not explicitly handled in the model base class.
To provide better flexibility, we should introduce a mechanism to switch between NumPy and CuPy based on user preference.

Proposed Solution:

• Convert np into a class attribute in the model base class.
• If the user wants to use the GPU, set np to CuPy (cupy).
• Otherwise, default to NumPy (numpy).

This change will allow seamless switching between CPU and GPU computations without modifying other parts of the code.

Additional Context:
This approach will improve performance for users who want GPU acceleration while maintaining compatibility for CPU-only environments.