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.Engine/Jobs/NestJobOptions.cs

@@ -5,11 +5,16 @@ namespace OpenNest;
 /// <summary>Immutable per-job options; selection never changes the legacy global registry.</summary>
 public sealed class NestJobOptions
 {
-    public NestJobOptions(string placementStrategy = "Default", int? maxPlates = null,
-        double salvageRate = 0, double minimumSalvageDimension = 0)
+    public NestJobOptions(
+        string placementStrategy = "Default",
+        int? maxPlates = null,
+        double salvageRate = 0,
+        double minimumSalvageDimension = 0
+    )
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(placementStrategy);
-        if (maxPlates <= 0) throw new ArgumentOutOfRangeException(nameof(maxPlates));
+        if (maxPlates <= 0)
+            throw new ArgumentOutOfRangeException(nameof(maxPlates));
         if (!double.IsFinite(salvageRate) || salvageRate < 0 || salvageRate > 1)
             throw new ArgumentOutOfRangeException(nameof(salvageRate));
         if (!double.IsFinite(minimumSalvageDimension) || minimumSalvageDimension < 0)
@@ -22,11 +27,13 @@ public sealed class NestJobOptions
 
     /// <summary>Fraction of eligible edge-offcut area credited by StockLadder (0..1).</summary>
     public double SalvageRate { get; }
+
     /// <summary>Both offcut dimensions must meet this caller-supplied minimum in job units.
     /// Zero disables credit; scraps and holes are never credited.</summary>
     public double MinimumSalvageDimension { get; }
 
     public string PlacementStrategy { get; }
+
     /// <summary>Maximum physical sheets to commit, or null for no explicit cap.</summary>
     public int? MaxPlates { get; }
 }