fix(mcp): add [McpServerToolType] attribute to all tool classes

Without this attribute, WithToolsFromAssembly does not discover
the tool methods and the server reports no tools capability.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

OpenNest.Mcp/Tools/SetupTools.cs

@@ -5,6 +5,7 @@ using OpenNest.Geometry;
 
 namespace OpenNest.Mcp.Tools
 {
+    [McpServerToolType]
     public class SetupTools
     {
         private readonly NestSession _session;