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.Core/Math/Angle.cs

@@ -90,8 +90,7 @@
             a1 = Angle.NormalizeRad(angle - a1);
             a2 = Angle.NormalizeRad(a2 - angle);
 
-            return diff >= a1 - Tolerance.Epsilon ||
-                   diff >= a2 - Tolerance.Epsilon;
+            return diff >= a1 - Tolerance.Epsilon || diff >= a2 - Tolerance.Epsilon;
         }
 
         /// <summary>
@@ -116,8 +115,7 @@
             a1 = Angle.NormalizeRad(angle - a1);
             a2 = Angle.NormalizeRad(a2 - angle);
 
-            return diff >= a1 - Tolerance.Epsilon ||
-                   diff >= a2 - Tolerance.Epsilon;
+            return diff >= a1 - Tolerance.Epsilon || diff >= a2 - Tolerance.Epsilon;
         }
     }
 }

OpenNest.Core/Math/ExpressionEvaluator.cs

@@ -10,13 +10,18 @@ namespace OpenNest.Math
     /// </summary>
     public static class ExpressionEvaluator
     {
-        public static double Evaluate(string expression, IReadOnlyDictionary<string, double> variables)
+        public static double Evaluate(
+            string expression,
+            IReadOnlyDictionary<string, double> variables
+        )
         {
             var parser = new Parser(expression, variables);
             var result = parser.ParseExpression();
             parser.SkipWhitespace();
             if (!parser.IsEnd)
-                throw new FormatException($"Unexpected character at position {parser.Position}: '{parser.Current}'");
+                throw new FormatException(
+                    $"Unexpected character at position {parser.Position}: '{parser.Current}'"
+                );
             return result;
         }
 
@@ -52,10 +57,12 @@ namespace OpenNest.Math
                 while (true)
                 {
                     SkipWhitespace();
-                    if (IsEnd) break;
+                    if (IsEnd)
+                        break;
 
                     var op = Current;
-                    if (op != '+' && op != '-') break;
+                    if (op != '+' && op != '-')
+                        break;
 
                     _pos++;
                     SkipWhitespace();
@@ -75,10 +82,12 @@ namespace OpenNest.Math
                 while (true)
                 {
                     SkipWhitespace();
-                    if (IsEnd) break;
+                    if (IsEnd)
+                        break;
 
                     var op = Current;
-                    if (op != '*' && op != '/') break;
+                    if (op != '*' && op != '/')
+                        break;
 
                     _pos++;
                     SkipWhitespace();
@@ -129,7 +138,10 @@ namespace OpenNest.Math
                 {
                     _pos++; // consume '$'
                     var start = _pos;
-                    while (_pos < _input.Length && (char.IsLetterOrDigit(_input[_pos]) || _input[_pos] == '_'))
+                    while (
+                        _pos < _input.Length
+                        && (char.IsLetterOrDigit(_input[_pos]) || _input[_pos] == '_')
+                    )
                         _pos++;
                     if (_pos == start)
                         throw new FormatException("Expected variable name after '$'.");
@@ -145,10 +157,19 @@ namespace OpenNest.Math
                     _pos++;
 
                 if (_pos == numStart)
-                    throw new FormatException($"Unexpected character '{Current}' at position {_pos}.");
+                    throw new FormatException(
+                        $"Unexpected character '{Current}' at position {_pos}."
+                    );
 
                 var numSpan = _input.Slice(numStart, _pos - numStart).ToString();
-                if (!double.TryParse(numSpan, NumberStyles.Float, CultureInfo.InvariantCulture, out var number))
+                if (
+                    !double.TryParse(
+                        numSpan,
+                        NumberStyles.Float,
+                        CultureInfo.InvariantCulture,
+                        out var number
+                    )
+                )
                     throw new FormatException($"Invalid number: '{numSpan}'");
 
                 return number;

OpenNest.Core/Math/Fraction.cs

@@ -7,8 +7,9 @@ namespace OpenNest.Math
 {
     public static class Fraction
     {
-        public static readonly Regex FractionRegex =
-            new Regex(@"((?<WholeNum>\d+)(\ |-))?(?<Fraction>\d+\/\d+)");
+        public static readonly Regex FractionRegex = new Regex(
+            @"((?<WholeNum>\d+)(\ |-))?(?<Fraction>\d+\/\d+)"
+        );
 
         public static bool IsValid(string s)
         {
@@ -59,7 +60,8 @@ namespace OpenNest.Math
         {
             var sb = new StringBuilder(input);
 
-            var fractionMatches = FractionRegex.Matches(sb.ToString())
+            var fractionMatches = FractionRegex
+                .Matches(sb.ToString())
                 .Cast<Match>()
                 .OrderByDescending(m => m.Index);