Refactor error handling and calculations in TheilU, Wmape, and TukeyBiweight classes; update buffer handling for consistency

- Updated buffer handling in TheilU and Wmape classes to ensure consistency after adding new values.
- Changed the resync interval constant in TukeyBiweight for better clarity.
- Refactored state structures to record structs in Gauss, Hann, Hp, Hpf, Kalman, Loess, Notch, and other filter classes for improved performance and readability.
- Enhanced numerical stability in Mama class calculations using Fused Multiply-Add (FMA) for precision.
- Added comprehensive tests for Atan2 validation to compare .NET's Math.Atan2 with PineScript's implementation, ensuring accuracy across various edge cases.
- Updated NDepend badges to reflect changes in classes, methods, and lines of code.

lib/statistics/sum/Sum.cs

@@ -45,7 +45,7 @@ public sealed class Sum : AbstractBase
     private readonly TValuePublishedHandler _handler;
 
     [StructLayout(LayoutKind.Auto)]
-    private struct State
+    private record struct State
     {
         public double Sum;           // Accumulated sum
         public double C;             // First-order compensation