style: apply CSharpier formatting to all C# sources

Repo-wide sweep with the pinned CSharpier 1.3.0 tool. Whitespace and
line-wrapping only; OpenNest.Engine.Tests (109) and OpenNest.IO.Tests
pass after reformat, full solution builds 0 errors.

Added .csharpierignore so csproj/config XML keeps its existing layout
(CSharpier's XML wrapping churns attributes with zero benefit).

Formatting is now enforceable: dotnet csharpier check . passes.

OpenNest.IO/Bom/BomAnalyzer.cs

@@ -62,8 +62,10 @@ namespace OpenNest.IO.Bom
 
                 var lookupName = item.FileName;
 
-                if (lookupName.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase)
-                    || lookupName.EndsWith(".dwg", StringComparison.OrdinalIgnoreCase))
+                if (
+                    lookupName.EndsWith(".dxf", StringComparison.OrdinalIgnoreCase)
+                    || lookupName.EndsWith(".dwg", StringComparison.OrdinalIgnoreCase)
+                )
                     lookupName = Path.GetFileNameWithoutExtension(lookupName);
 
                 if (!folderExists)
@@ -86,13 +88,13 @@ namespace OpenNest.IO.Bom
                 .GroupBy(p => new
                 {
                     Material = (p.Item.Material ?? "").ToUpperInvariant(),
-                    Thickness = p.Item.Thickness.Value
+                    Thickness = p.Item.Thickness.Value,
                 })
                 .Select(g => new MaterialGroup
                 {
                     Material = g.First().Item.Material ?? "",
                     Thickness = g.Key.Thickness,
-                    Parts = g.ToList()
+                    Parts = g.ToList(),
                 })
                 .OrderBy(g => g.Material)
                 .ThenBy(g => g.Thickness)

OpenNest.IO/Bom/BomReader.cs

@@ -1,8 +1,8 @@
-using ClosedXML.Excel;
 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Reflection;
+using ClosedXML.Excel;
 
 namespace OpenNest.IO.Bom
 {
@@ -20,7 +20,9 @@ namespace OpenNest.IO.Bom
         private IXLWorksheet GetPartsWorksheet()
         {
             if (!workbook.TryGetWorksheet("Parts", out var worksheet))
-                throw new InvalidOperationException("BOM file does not contain a 'Parts' worksheet.");
+                throw new InvalidOperationException(
+                    "BOM file does not contain a 'Parts' worksheet."
+                );
             return worksheet;
         }
 
@@ -41,7 +43,8 @@ namespace OpenNest.IO.Bom
                 for (var columnIndex = 1; columnIndex <= lastColumn; columnIndex++)
                 {
                     var cell = worksheet.Cell(1, columnIndex);
-                    if (cell.IsEmpty()) continue;
+                    if (cell.IsEmpty())
+                        continue;
 
                     var excelColumnName = cell.GetString().ToUpper();
                     var isMatch = classColumnNames.Any(n => n == excelColumnName);

OpenNest.IO/Bom/CellExtensions.cs

@@ -6,17 +6,23 @@ namespace OpenNest.IO.Bom
     {
         public static int? ToIntOrNull(this IXLCell cell)
         {
-            if (cell.IsEmpty()) return null;
-            if (cell.DataType == XLDataType.Number) return (int)cell.GetDouble();
-            if (int.TryParse(cell.GetString(), out var i)) return i;
+            if (cell.IsEmpty())
+                return null;
+            if (cell.DataType == XLDataType.Number)
+                return (int)cell.GetDouble();
+            if (int.TryParse(cell.GetString(), out var i))
+                return i;
             return null;
         }
 
         public static double? ToDoubleOrNull(this IXLCell cell)
         {
-            if (cell.IsEmpty()) return null;
-            if (cell.DataType == XLDataType.Number) return cell.GetDouble();
-            if (double.TryParse(cell.GetString(), out var result)) return result;
+            if (cell.IsEmpty())
+                return null;
+            if (cell.DataType == XLDataType.Number)
+                return cell.GetDouble();
+            if (double.TryParse(cell.GetString(), out var result))
+                return result;
             return null;
         }
     }