feat: add Bends property to Drawing, GrainAngle to Plate

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

OpenNest.Core/Drawing.cs

@@ -1,6 +1,8 @@
-using OpenNest.CNC;
+using OpenNest.Bending;
+using OpenNest.CNC;
 using OpenNest.Converters;
 using OpenNest.Geometry;
+using System.Collections.Generic;
 using System.Drawing;
 using System.Linq;
 using System.Threading;
@@ -62,6 +64,8 @@ namespace OpenNest
 
         public SourceInfo Source { get; set; }
 
+        public List<Bend> Bends { get; set; } = new List<Bend>();
+
         public double Area { get; protected set; }
 
         public void UpdateArea()

OpenNest.Core/Plate.cs

@@ -88,6 +88,11 @@ namespace OpenNest
         /// </summary>
         public Material Material { get; set; }
 
+        /// <summary>
+        /// Material grain direction in radians. 0 = horizontal.
+        /// </summary>
+        public double GrainAngle { get; set; }
+
         /// <summary>
         /// The parts that the plate contains.
         /// </summary>