Update

This update focuses on improving code structure and adding new functionalities for better readability and reproducibility.

Key Updates:

• Project Refactoring: The project structure has been refactored from a flat layout to a src layout.
• Heatmap Generation Callback: Added a new callback specifically for generating heatmaps. During testing, these heatmaps are automatically logged to TensorBoard when properly configured. Mentioned in #1.
• Image Preprocessing: Added image preprocessing implementation (DDR images).