feat: Add new CodeQL extension for C# and SonarLint configuration

- Introduced a new CodeQL extension for C# in `.github/codeql/extensions/quantalib-csharp/codeql-pack.yml`.
- Added SonarLint configuration in `.sonarlint/CSharp/SonarLint.xml` and `.sonarlint/csharp.ruleset` to suppress specific rules for high-performance indicators.
- Removed outdated `.vscode/launch.json` configurations.
- Updated `.vscode/tasks.json` to streamline build and test tasks, including renaming and consolidating tasks.
- Modified `Directory.Build.props` to enhance SARIF output directory handling and integrate SonarLint rules.
- Refactored various indicator classes to improve code clarity and maintainability, including updates to method parameters for consistency.
- Added XML documentation comments to several classes and methods for better code understanding.
- Improved numerical stability in calculations by replacing direct comparisons with `double.Epsilon` checks in multiple classes.

lib/numerics/sigmoid/Sigmoid.cs

@@ -30,6 +30,9 @@ public sealed class Sigmoid : AbstractBase
 
     public override bool IsHot => true;  // No warmup needed
 
+    /// <summary>
+    /// Initializes a new Sigmoid indicator with specified steepness and midpoint.
+    /// </summary>
     /// <param name="k">Steepness factor (default 1.0). Higher values create steeper transitions.</param>
     /// <param name="x0">Midpoint value where output equals 0.5 (default 0.0).</param>
     public Sigmoid(double k = 1.0, double x0 = 0.0)
@@ -43,6 +46,9 @@ public sealed class Sigmoid : AbstractBase
         WarmupPeriod = 0;
     }
 
+    /// <summary>
+    /// Initializes a new Sigmoid indicator with source for event-based chaining.
+    /// </summary>
     /// <param name="source">Source indicator for chaining</param>
     /// <param name="k">Steepness factor (default 1.0)</param>
     /// <param name="x0">Midpoint value (default 0.0)</param>