refactor: 重构项目架构，拆分代码到模块化目录

将单文件tts_server.go重构为模块化项目结构，拆分出common、dto、middleware、router、controller、service、adapter、setting等目录，优化代码组织提升可维护性

middleware/logger.go

@@ -0,0 +1,35 @@
+package middleware
+
+import (
+	"log"
+	"net/http"
+	"time"
+)
+
+type statusRecorder struct {
+	http.ResponseWriter
+	statusCode int
+}
+
+func (rec *statusRecorder) WriteHeader(code int) {
+	rec.statusCode = code
+	rec.ResponseWriter.WriteHeader(code)
+}
+
+func Logger(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/health" {
+			start := time.Now()
+			next.ServeHTTP(w, r)
+			log.Printf("%s %s %s %v", r.Method, r.RequestURI, r.RemoteAddr, time.Since(start))
+			return
+		}
+
+		start := time.Now()
+		rec := &statusRecorder{ResponseWriter: w, statusCode: http.StatusOK}
+		next.ServeHTTP(rec, r)
+		duration := time.Since(start)
+
+		log.Printf("%s %s %s %d %v", r.Method, r.RequestURI, r.RemoteAddr, rec.statusCode, duration)
+	})
+}