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/errors/rsquared/Rsquared.cs

@@ -110,25 +110,22 @@ public sealed class Rsquared : AbstractBase
         {
             _state = _p_state;
 
-            // Update actual buffer
-            double removedActual = _actualBuffer.Count == _actualBuffer.Capacity ? _actualBuffer.Oldest : 0.0;
-            _state.ActualSum = _state.ActualSum - removedActual + actualVal;
+            // Bar correction: update buffers and recalculate sums
             _actualBuffer.UpdateNewest(actualVal);
-            _state.ActualSum = _actualBuffer.RecalculateSum();
 
             // Calculate mean and errors
-            double mean = _state.ActualSum / _actualBuffer.Count;
+            double mean = _actualBuffer.RecalculateSum() / _actualBuffer.Count;
+            _state.ActualSum = _actualBuffer.RecalculateSum();
+
             double residual = actualVal - predictedVal;
             double totalDev = actualVal - mean;
             double sqResidual = residual * residual;
             double sqTotal = totalDev * totalDev;
 
-            // Update squared residual buffer
             _sqResidualBuffer.UpdateNewest(sqResidual);
-            _state.SqResidualSum = _sqResidualBuffer.RecalculateSum();
-
-            // Update squared total buffer
             _sqTotalBuffer.UpdateNewest(sqTotal);
+
+            _state.SqResidualSum = _sqResidualBuffer.RecalculateSum();
             _state.SqTotalSum = _sqTotalBuffer.RecalculateSum();
         }