feat: scaffold OpenNest.Mcp project with session state

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

OpenNest.Mcp/Program.cs

@@ -0,0 +1,15 @@
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using ModelContextProtocol.Server;
+using OpenNest.Mcp;
+
+var builder = Host.CreateApplicationBuilder(args);
+
+builder.Services.AddSingleton<NestSession>();
+builder.Services
+    .AddMcpServer()
+    .WithStdioServerTransport()
+    .WithToolsFromAssembly(typeof(Program).Assembly);
+
+var app = builder.Build();
+await app.RunAsync();