Update DockerSpec to accept engineering directory for Claude Dockerfile path

Author: gfraiteur

src/PostSharp.Engineering.BuildTools/ContinuousIntegration/TeamCity/Generation/TeamCitySettingsFile.cs

@@ -206,7 +206,7 @@ private static TeamCityBuildConfiguration CreateUpstreamMergeConfiguration( Prod
         var product = productProperties.Product;
 
         // Use Claude Dockerfile for upstream merge to enable AI-assisted conflict resolution
-        var claudeDockerSpec = product.DockerSpec?.WithClaudeDockerfile();
+        var claudeDockerSpec = product.DockerSpec?.WithClaudeDockerfile( product.EngineeringDirectory );
 
         // Dependencies on UpstreamMerge of dependent repos (for cascading merge order).
         // Only consolidated products have snapshot dependencies - normal products merge independently.

src/PostSharp.Engineering.BuildTools/Docker/DockerSpec.cs

@@ -4,5 +4,5 @@ namespace PostSharp.Engineering.BuildTools.Docker;
 
 public record DockerSpec( string ImageName, int? Memory = null, string? Dockerfile = null )
 {
-    public DockerSpec WithClaudeDockerfile() => this with { Dockerfile = "Dockerfile.claude" };
+    public DockerSpec WithClaudeDockerfile( string engineeringDirectory ) => this with { Dockerfile = $"{engineeringDirectory}/docker/Dockerfile.claude" };
 }