feat: sudoku added

[ksskumarsahil006-sketch]

Description

Added a Sudoku Generator and Solver in C++ using backtracking and randomization.

• Generates Sudoku puzzles of multiple difficulty levels (easy, medium, hard, expert)
• Solves puzzles using recursive backtracking
• Ensures unique solutions
• Uses std::shuffle for better randomization (replacing deprecated random_shuffle)

Semver Changes

• Patch (bug fix, no new features)
• Minor (new features, no breaking changes)
• Major (breaking changes)

Issues

Closes #52

Checklist

• I have tested the code locally and verified correct Sudoku generation and solving.
• Code compiles without warnings or errors.
• Follows the repository’s folder structure (Src/Sudoku_Generator_Solver/Game.cpp).
• I have read the Contributing Guidelines.
• Added proper comments and clear formatting for maintainability.

[ksskumarsahil006-sketch]

@prajwal3114 please review my PR sir

[ksskumarsahil006-sketch]

@prajwal3114 please review my PR sir