feat: add AdvancedSequencer with row grouping and serpentine

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

OpenNest.Engine/Sequencing/AdvancedSequencer.cs

@@ -0,0 +1,96 @@
+using System.Collections.Generic;
+using System.Linq;
+using OpenNest.CNC.CuttingStrategy;
+using OpenNest.Math;
+
+namespace OpenNest.Engine.Sequencing
+{
+    public class AdvancedSequencer : IPartSequencer
+    {
+        private readonly SequenceParameters _parameters;
+
+        public AdvancedSequencer(SequenceParameters parameters)
+        {
+            _parameters = parameters;
+        }
+
+        public List<SequencedPart> Sequence(IReadOnlyList<Part> parts, Plate plate)
+        {
+            if (parts.Count == 0)
+                return new List<SequencedPart>();
+
+            var exit = PlateHelper.GetExitPoint(plate);
+
+            // Group parts into rows by Y proximity
+            var rows = GroupIntoRows(parts, _parameters.MinDistanceBetweenRowsColumns);
+
+            // Sort rows bottom-to-top (ascending Y)
+            rows.Sort((a, b) => a.RowY.CompareTo(b.RowY));
+
+            // Determine initial direction based on exit point
+            var leftToRight = exit.X > plate.Size.Width * 0.5;
+
+            var result = new List<SequencedPart>(parts.Count);
+            foreach (var row in rows)
+            {
+                var sorted = leftToRight
+                    ? row.Parts.OrderBy(p => p.BoundingBox.Center.X).ToList()
+                    : row.Parts.OrderByDescending(p => p.BoundingBox.Center.X).ToList();
+
+                foreach (var p in sorted)
+                    result.Add(new SequencedPart { Part = p });
+
+                if (_parameters.AlternateRowsColumns)
+                    leftToRight = !leftToRight;
+            }
+
+            return result;
+        }
+
+        private static List<PartRow> GroupIntoRows(IReadOnlyList<Part> parts, double minDistance)
+        {
+            // Sort parts by Y center
+            var sorted = parts
+                .OrderBy(p => p.BoundingBox.Center.Y)
+                .ToList();
+
+            var rows = new List<PartRow>();
+
+            foreach (var part in sorted)
+            {
+                var y = part.BoundingBox.Center.Y;
+                var placed = false;
+
+                foreach (var row in rows)
+                {
+                    if (System.Math.Abs(y - row.RowY) <= minDistance + Tolerance.Epsilon)
+                    {
+                        row.Parts.Add(part);
+                        placed = true;
+                        break;
+                    }
+                }
+
+                if (!placed)
+                {
+                    var row = new PartRow(y);
+                    row.Parts.Add(part);
+                    rows.Add(row);
+                }
+            }
+
+            return rows;
+        }
+
+        private class PartRow
+        {
+            public double RowY { get; }
+            public List<Part> Parts { get; } = new List<Part>();
+
+            public PartRow(double rowY)
+            {
+                RowY = rowY;
+            }
+        }
+    }
+}