Refactor trend indicators to use record structs for state management

test_record_struct.cs

@@ -0,0 +1,23 @@
+using System;
+
+namespace QuanTAlib;
+
+public class RecordStructTest
+{
+    private record struct State(double Val, bool Flag);
+
+    public static void Run()
+    {
+        var s1 = new State(1.0, true);
+        var s2 = new State(1.0, true);
+        var s3 = new State(2.0, false);
+
+        Console.WriteLine($"s1 == s2: {s1 == s2}"); // Should be True
+        Console.WriteLine($"s1 == s3: {s1 == s3}"); // Should be False
+        Console.WriteLine($"s1 equals s2: {s1.Equals(s2)}"); // Should be True
+        
+        // Verify mutability
+        s1.Val = 3.0;
+        Console.WriteLine($"s1 modified: {s1.Val}");
+    }
+}