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/Report.Drawing.cs

@@ -0,0 +1,51 @@
+namespace PepLib.Models
+{
+    public partial class Report
+    {
+        public class Drawing
+        {
+            public string Customer { get; set; }
+
+            public string Name { get; set; }
+
+            public string Revision { get; set; }
+
+            public int QtyRequired { get; set; }
+
+            public int QtyNested { get; set; }
+
+            public int QtyRemaining
+            {
+                get { return QtyRequired - QtyNested; }
+            }
+
+            public double CutDistance { get; set; }
+
+            public double ScribeDistance { get; set; }
+
+            public double BevelDistance { get; set; }
+
+            public TimeSpan TotalCutTime { get; set; }
+
+            public int PierceCount { get; set; }
+
+            public int IntersectionCount { get; set; }
+
+            public double Area1 { get; set; }
+
+            public double Area2 { get; set; }
+
+            public bool IncludeRemnantInCost { get; set; }
+
+            public double NetWeight1 { get; set; }
+
+            public double NetWeight2 { get; set; }
+
+            public double GrossWeight { get; set; }
+
+            public double PercentOfMaterial { get; set; }
+
+            public double PercentOfCutTime { get; set; }
+        }
+    }
+}