Add K-Nearest Neighbor (KNN) implementation and Test

[ngtduc693]

Summary

K-Nearest Neighbors (KNN) classifier is a commonly used algorithm in Machine Learning/AI

Changes

• Implement KNN algorithm
• Unit test covering all code paths above
• Update README to document the new algorithm

Unit Test Passed Evidence

Build Passed Evidence

• 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

❌ Patch coverage is 97.82609% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 96.68%. Comparing base (a8af880) to head (76400bd).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
Algorithms/MachineLearning/KNearestNeighbors.cs	97.82%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #542   +/-   ##
=======================================
  Coverage   96.67%   96.68%           
=======================================
  Files         279      280    +1     
  Lines       11013    11059   +46     
  Branches     1568     1577    +9     
=======================================
+ Hits        10647    10692   +45     
  Misses        232      232           
- Partials      134      135    +1     

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[Copilot]

Pull Request Overview

This PR adds a K-Nearest Neighbors (KNN) classifier implementation to the machine learning algorithms collection. The implementation includes a generic classifier that can work with any label type and uses Euclidean distance for neighbor calculations.

• Added a complete KNN classifier with proper error handling and validation
• Comprehensive unit tests covering all code paths including edge cases and error conditions
• Updated README to document the new algorithm in the machine learning section

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
README.md	Added KNN entry to the machine learning algorithms list
Algorithms/MachineLearning/KNearestNeighbors.cs	Complete KNN implementation with generic label support and Euclidean distance calculation
Algorithms.Tests/MachineLearning/KNearestNeighborsTests.cs	Comprehensive test suite covering all functionality and error cases

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[siriak]

Please resolve Codacy issues

[ngtduc693]

Please resolve Codacy issues

I'm done, thanks @siriak

[Copilot]

Pull Request Overview

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

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[siriak]

Looks good, thanks!