Improve existing QR code generator (qr.py)

[Luckman-Khan]

Hello! This PR replaces the existing qr.py script with a more robust and user-friendly version.

Key Improvements:

• Dynamic Filenames: Generates a unique, timestamped PNG file for each run to prevent overwriting previous QR codes.
• User-Friendly Location: Saves the image directly to the user's Downloads folder for easy access.
• Clear Feedback: Prints a confirmation message to the console with the exact save path.
• Format Change: Uses PNG, a more common and easily shareable format for this use case.

I have tested the script locally and it runs without errors. I believe these changes make the program a much more practical utility for the repository.