Added unit test project for HelperClasses and tests for IntegerRange.cs. Implemented IEnumerable on IntegerRange.

AoC_2025/Day05.cs

@@ -106,7 +106,7 @@ public class Day05 : IPuzzleSolver<long>
     
     private static IEnumerable<long> CountIdsInRanges(IEnumerable<IntegerRange> combinedRanges)
     {
-        var countIdsInRanges = combinedRanges.Select(range => range.Count());
+        var countIdsInRanges = combinedRanges.Select(range => range.Count);
         return countIdsInRanges;
     }
 }