mcp/examples: HTTP server example with a simple client built-in (#168)

I'm adding a practical example of an MCP with HTTP streaming: both
client and server. Those are useful for testing real-world applications.

examples/http/logging_middleware.go

@@ -0,0 +1,51 @@
+// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"log"
+	"net/http"
+	"time"
+)
+
+// responseWriter wraps http.ResponseWriter to capture the status code.
+type responseWriter struct {
+	http.ResponseWriter
+	statusCode int
+}
+
+func (rw *responseWriter) WriteHeader(code int) {
+	rw.statusCode = code
+	rw.ResponseWriter.WriteHeader(code)
+}
+
+func loggingHandler(handler http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+
+		// Create a response writer wrapper to capture status code.
+		wrapped := &responseWriter{ResponseWriter: w, statusCode: http.StatusOK}
+
+		// Log request details.
+		log.Printf("[REQUEST] %s | %s | %s %s",
+			start.Format(time.RFC3339),
+			r.RemoteAddr,
+			r.Method,
+			r.URL.Path)
+
+		// Call the actual handler.
+		handler.ServeHTTP(wrapped, r)
+
+		// Log response details.
+		duration := time.Since(start)
+		log.Printf("[RESPONSE] %s | %s | %s %s | Status: %d | Duration: %v",
+			time.Now().Format(time.RFC3339),
+			r.RemoteAddr,
+			r.Method,
+			r.URL.Path,
+			wrapped.statusCode,
+			duration)
+	})
+}