feat: add local G2 smoothing contracts

ClumsyPilot/ParkrobTrajplanner/PathSmoothing/Contracts/SmoothedPathPoint.cs

@@ -17,6 +17,36 @@ public sealed class SmoothedPathPoint
         double bodyClearanceMeters,
         bool isGearSwitchPoint,
         SmoothedPathPointSource source)
+        : this(
+            xMeters,
+            yMeters,
+            headingRadians,
+            unwrappedHeadingRadians,
+            arcLengthMeters,
+            direction,
+            geometricCurvaturePerMeter,
+            vehicleCurvaturePerMeter,
+            0d,
+            bodyClearanceMeters,
+            isGearSwitchPoint,
+            source)
+    {
+    }
+
+    /// <summary>创建带有车辆曲率对弧长导数的不可变采样点。</summary>
+    public SmoothedPathPoint(
+        double xMeters,
+        double yMeters,
+        double headingRadians,
+        double unwrappedHeadingRadians,
+        double arcLengthMeters,
+        TravelDirection direction,
+        double geometricCurvaturePerMeter,
+        double vehicleCurvaturePerMeter,
+        double vehicleCurvatureDerivativePerSquareMeter,
+        double bodyClearanceMeters,
+        bool isGearSwitchPoint,
+        SmoothedPathPointSource source)
     {
         X = xMeters;
         Y = yMeters;
@@ -26,6 +56,7 @@ public sealed class SmoothedPathPoint
         Direction = direction;
         GeometricCurvature = geometricCurvaturePerMeter;
         VehicleCurvature = vehicleCurvaturePerMeter;
+        VehicleCurvatureDerivative = vehicleCurvatureDerivativePerSquareMeter;
         BodyClearance = bodyClearanceMeters;
         IsGearSwitchPoint = isGearSwitchPoint;
         Source = source;
@@ -55,6 +86,9 @@ public sealed class SmoothedPathPoint
     /// <summary>车辆模型使用的有符号曲率，单位 1/m。</summary>
     public double VehicleCurvature { get; }
 
+    /// <summary>车辆曲率对弧长的导数 dκ/ds，单位 1/m²。</summary>
+    public double VehicleCurvatureDerivative { get; }
+
     /// <summary>扩大车体后的保守净空下界，单位 m。</summary>
     public double BodyClearance { get; }