Add duplicate_file_finder.py utility script

[Sumit6258]

This PR adds a utility script duplicate_file_finder.py.

Features:

• Scans a directory recursively
• Detects duplicate files using SHA256 hashing
• Prints duplicate file pairs

This script may help users clean up storage and learn about hashing in Python.

The script follows the simple standalone style used in this repository.

[Sumit6258]

The second file I added is:
typing_speed_test.py - simple CLI typing speed tester

This PR adds a simple command-line typing speed test script.

Features:

• Random sentence typing test
• Calculates typing speed in words per minute (WPM)
• Measures typing accuracy
• Uses only Python standard library

The script is beginner-friendly and demonstrates concepts such as timing, string comparison, and user input.