fix: keep MCP protocol stdout clean

PepMcp/Program.cs

@@ -1,7 +1,14 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Logging;
 
 var builder = Host.CreateApplicationBuilder(args);
+
+// MCP stdio requires stdout to contain JSON-RPC messages only. Route every
+// Microsoft logger event to stderr so it cannot corrupt the protocol stream.
+builder.Logging.ClearProviders();
+builder.Logging.AddConsole(options => options.LogToStandardErrorThreshold = LogLevel.Trace);
+
 builder.Services
     .AddMcpServer()
     .WithStdioServerTransport()