Restructured main.py with simple UI

[Sajin-sjn]

QR Code Generator - UI Enhancement and Organized QR Code Saving

Key Improvements :

1. Enhanced UI : Redesigned for a cleaner, modern look with improved font styles, colors, and layout.
2. QR Code Preview : Added a preview section for users to view the generated QR code before saving.
3. Organized File Saving: QR codes are now saved in a static folder, with automatic directory creation and unique filenames based on timestamps.

These changes improve usability, provide better visual feedback, and ensure organized QR code management.

Feel free to review the changes, and I look forward to your feedback! 😄