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/CandidateProgressBridge.cs

@@ -9,18 +9,25 @@ namespace OpenNest;
 /// </summary>
 internal static class CandidateProgressBridge
 {
-    internal static IProgress<NestProgress> Create(IProgress<NestJobProgress> progress, string stockId)
+    internal static IProgress<NestProgress> Create(
+        IProgress<NestJobProgress> progress,
+        string stockId
+    )
     {
-        if (progress == null) return null;
+        if (progress == null)
+            return null;
         return new LegacyToJob(progress, stockId);
     }
 
-    private sealed class LegacyToJob(IProgress<NestJobProgress> progress, string stockId) : IProgress<NestProgress>
+    private sealed class LegacyToJob(IProgress<NestJobProgress> progress, string stockId)
+        : IProgress<NestProgress>
     {
         public void Report(NestProgress value)
         {
             ArgumentNullException.ThrowIfNull(value);
-            progress.Report(new NestJobProgress(NestJobStage.EvaluatingCandidate, stockId, -1, 0, 0, value));
+            progress.Report(
+                new NestJobProgress(NestJobStage.EvaluatingCandidate, stockId, -1, 0, 0, value)
+            );
         }
     }
 }