Add implementation for Open Knight Tour

[Kalkwst]

• I have performed a self-review of my code
• My code follows the style guidelines of this project
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Comments in areas I changed are up to date
• I have added comments to hard-to-understand areas of my code
• I have made corresponding changes to the README.md

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.70%. Comparing base (c6c3aa2) to head (8c52645).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #547      +/-   ##
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+ Coverage   96.68%   96.70%   +0.01%     
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  Files         280      281       +1     
  Lines       11059    11123      +64     
  Branches     1577     1590      +13     
==========================================
+ Hits        10692    10756      +64     
  Misses        232      232              
  Partials      135      135              

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[Copilot]

Pull Request Overview

This PR adds an implementation of the Open Knight Tour problem using depth-first search with backtracking. The algorithm finds a sequence of knight moves that visits every square on an n×n chessboard exactly once.

Key changes:

• Implements backtracking algorithm to solve the Knight Tour problem for square boards
• Adds comprehensive test suite covering edge cases, invalid inputs, and solution validation
• Updates documentation to include the new Knight Tour algorithm

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
README.md	Adds Knight Tour entry to the algorithms index
Algorithms/Problems/KnightTour/OpenKnightTour.cs	Implements the Open Knight Tour algorithm using DFS with backtracking
Algorithms.Tests/Problems/KnightTour/OpenKnightTourTests.cs	Provides comprehensive test coverage including validation helpers and edge cases

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[siriak]

Looks good, thanks!