refactor(nesting): unify console MCP and API validation and commit policies

OpenNest.Mcp/Program.cs

@@ -1,16 +1,23 @@
+using System;
+using System.IO;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
+using OpenNest.Engine.Jobs;
 using OpenNest.Mcp;
 
+NestingEngineRegistry.LoadPlugins(Path.Combine(AppContext.BaseDirectory, "Engines"));
 var builder = Host.CreateApplicationBuilder(args);
 
 // stdout carries the JSON-RPC stream; console logs must go to stderr or they corrupt it.
 builder.Logging.AddConsole(o => o.LogToStandardErrorThreshold = LogLevel.Trace);
 
+using var toolGate = new SessionToolGate();
 builder.Services.AddSingleton<NestSession>();
 builder
     .Services.AddMcpServer()
+    .WithRequestFilters(filters => filters.AddCallToolFilter(
+        next => (context, token) => toolGate.RunAsync(ct => next(context, ct), token)))
     .WithStdioServerTransport()
     .WithToolsFromAssembly(typeof(Program).Assembly);