Rename SawCut library to CutList.Core

Rename the core library project from SawCut to CutList.Core for consistent
branding across the solution. This includes:
- Rename project folder and .csproj file
- Update namespace from SawCut to CutList.Core
- Update all using statements and project references

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

CutList.Core/BinGroup.cs

@@ -0,0 +1,51 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace CutList.Core
+{
+    /// <summary>
+    /// Represents a group of identical bins (bins with the same items in the same order).
+    /// Used for displaying consolidated results.
+    /// </summary>
+    public class BinGroup
+    {
+        public BinGroup(Bin representativeBin, int count)
+        {
+            if (representativeBin == null)
+                throw new ArgumentNullException(nameof(representativeBin));
+
+            if (count <= 0)
+                throw new ArgumentException("Count must be greater than zero", nameof(count));
+
+            RepresentativeBin = representativeBin;
+            Count = count;
+        }
+
+        /// <summary>
+        /// A representative bin from this group (all bins in the group are identical).
+        /// </summary>
+        public Bin RepresentativeBin { get; }
+
+        /// <summary>
+        /// The number of identical bins in this group.
+        /// </summary>
+        public int Count { get; }
+
+        // Properties that delegate to the representative bin for data binding
+        public double Spacing => RepresentativeBin.Spacing;
+        public double Length => RepresentativeBin.Length;
+        public double UsedLength => RepresentativeBin.UsedLength;
+        public double RemainingLength => RepresentativeBin.RemainingLength;
+        public double Utilization => RepresentativeBin.Utilization;
+        public IReadOnlyList<BinItem> Items => RepresentativeBin.Items;
+
+        public override string ToString()
+        {
+            if (Count == 1)
+                return RepresentativeBin.ToString();
+
+            return $"{RepresentativeBin} (x{Count})";
+        }
+    }
+}