refactor(PepLib.Core): reorganize files into logical folder structure

Move 38 files from root directory into organized subfolders:
- Enums/ (7 files): StatusType, ApplicationType, DrawingType, etc.
- Geometry/ (5 files): Vector, Box, Size, Spacing, Node
- Models/ (15 files): Nest, Plate, Part, Program, Report, etc.
- Utilities/ (7 files): MathHelper, Tolerance, ZipHelper, etc.
- Extensions/ (2 files): PartListExtensions, PlateListExtensions
- Interfaces/ (1 file): IMovable

Update namespaces to follow folder hierarchy (e.g., PepLib.Models).
Add GlobalUsings.cs for internal backward compatibility.
Update Codes/ and IO/ files with new using statements.
Update PepApi.Core consumers to reference new namespaces.

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

PepLib.Core/Models/Nest.cs

@@ -0,0 +1,131 @@
+using PepLib.Codes;
+using PepLib.IO;
+
+namespace PepLib.Models
+{
+    public class Nest
+    {
+        public Nest()
+        {
+            Report = new Report();
+            Loops = new List<Loop>();
+            Plates = new List<Plate>();
+            Drawings = new List<NestDrawing>();
+        }
+
+        public Report Report { get; set; }
+
+        public List<Loop> Loops { get; set; }
+
+        public List<Plate> Plates { get; set; }
+
+        public List<NestDrawing> Drawings { get; set; }
+
+        public void ResolveLoops()
+        {
+            for (int i = 0; i < Loops.Count; ++i)
+            {
+                var loop = Loops[i];
+                ResolveLoops(loop);
+            }
+        }
+
+        private void ResolveLoops(Program pgm)
+        {
+            for (int i = 0; i < pgm.Count; ++i)
+            {
+                var code = pgm[i];
+
+                if (code.CodeType() != CodeType.SubProgramCall)
+                    continue;
+
+                var subpgmcall = (SubProgramCall)code;
+
+                var loop = GetLoop(subpgmcall.LoopId);
+
+                if (loop == null)
+                    throw new Exception("Loop not found");
+
+                subpgmcall.Loop = loop;
+            }
+        }
+
+        public int GetQtyNested(string drawing)
+        {
+            int qty = 0;
+
+            foreach (var plate in Plates)
+                qty += plate.GetQtyNested(drawing);
+
+            return qty;
+        }
+
+        private Loop GetLoop(string name)
+        {
+            for (int i = 0; i < Loops.Count; ++i)
+            {
+                if (Loops[i].Name == name)
+                    return Loops[i];
+            }
+
+            return null;
+        }
+
+        public Loop GetLoop(int id)
+        {
+            var ext = $".loop-{id.ToString().PadLeft(3, '0')}";
+
+            for (int i = 0; i < Loops.Count; ++i)
+            {
+                if (Loops[i].Name.EndsWith(ext))
+                    return Loops[i];
+            }
+
+            return null;
+        }
+
+        public static Nest Load(string nestfile)
+        {
+            var reader = new NestReader();
+            reader.Read(nestfile);
+            return reader.Nest;
+        }
+
+        public static Nest Load(Stream stream)
+        {
+            var reader = new NestReader();
+            reader.Read(stream);
+            return reader.Nest;
+        }
+
+        public static bool TryLoad(string nestfile, out Nest nest)
+        {
+            try
+            {
+                nest = Load(nestfile);
+            }
+            catch (Exception)
+            {
+                nest = null;
+                return false;
+            }
+
+            return true;
+        }
+
+        public static bool TryLoad(Stream stream, out Nest nest)
+        {
+            try
+            {
+                nest = Load(stream);
+            }
+            catch (Exception)
+            {
+                nest = null;
+                return false;
+            }
+
+            return true;
+        }
+    }
+}