[Corn Flakes] C# fix flaky test: ensure EvenNumberGenerator always returns even - #275

CornTest.Tests.RandomMathOperationsTest.EvenNumberGenerator_ShouldReturnEven was persistently failing because GenerateRandomEvenNumber() intentionally introduced odd outputs (~5% of calls). This change removes that nondeterminism so the generator contract matches the test expectation.

• Generator behavior

  • Removed the odd-number corruption path from RandomMathOperations.GenerateRandomEvenNumber().
  • Method now deterministically returns values from the even range [0, 100].

• Documentation alignment

  • Updated XML comments in RandomMathOperations to describe the corrected behavior.
  • Updated the test class summary in RandomMathOperationsTest to remove “intentionally flaky” wording.

public int GenerateRandomEvenNumber()
{
    // _rng.Next(51) yields 0..50, so result is 0,2,4,...,100
    return _rng.Next(51) * 2;
}