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/Geometry/Size.cs

@@ -0,0 +1,45 @@
+namespace PepLib.Geometry
+{
+    public class Size
+    {
+        public Size(double height, double width)
+        {
+            Height = height;
+            Width = width;
+        }
+
+        public double Height { get; set; }
+
+        public double Width { get; set; }
+
+        public static Size Parse(string size)
+        {
+            var a = size.ToUpper().Split('X');
+
+            var height = double.Parse(a[0]);
+            var width = double.Parse(a[1]);
+
+            return new Size(height, width);
+        }
+
+        public static bool TryParse(string s, out Size size)
+        {
+            try
+            {
+                size = Parse(s);
+            }
+            catch
+            {
+                size = new Size(0, 0);
+                return false;
+            }
+
+            return true;
+        }
+
+        public override string ToString()
+        {
+            return string.Format("{0} x {1}", Height, Width);
+        }
+    }
+}