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

service/stats.go

@@ -0,0 +1,90 @@
+package service
+
+import (
+	"fmt"
+	"runtime"
+	"sync"
+	"time"
+
+	"github.com/volcano-tts/tts-api/common"
+)
+
+type Stats struct {
+	totalRequests       int64
+	successfulRequests  int64
+	failedRequests      int64
+	totalResponseTime   time.Duration
+	recentResponseTimes []float64
+	responseTimesIndex  int
+	lastErrors          []string
+	errorsIndex         int
+	mutex               sync.RWMutex
+}
+
+var GlobalStats *Stats
+
+func InitStats() {
+	GlobalStats = &Stats{
+		recentResponseTimes: make([]float64, common.MaxResponseTimes),
+		lastErrors:          make([]string, common.MaxErrors),
+	}
+}
+
+func (s *Stats) AddRequest(success bool, responseTime time.Duration, errMsg string) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+
+	s.totalRequests++
+	s.totalResponseTime += responseTime
+
+	s.recentResponseTimes[s.responseTimesIndex] = responseTime.Seconds() * 1000
+	s.responseTimesIndex = (s.responseTimesIndex + 1) % common.MaxResponseTimes
+
+	if success {
+		s.successfulRequests++
+	} else {
+		s.failedRequests++
+		if errMsg != "" {
+			errInfo := fmt.Sprintf("%s: %s", time.Now().Format(time.RFC3339), errMsg)
+			s.lastErrors[s.errorsIndex] = errInfo
+			s.errorsIndex = (s.errorsIndex + 1) % common.MaxErrors
+		}
+	}
+}
+
+func (s *Stats) GetSnapshot() (totalRequests int64, successfulRequests int64, failedRequests int64,
+	totalResponseTime time.Duration, recentResponseTimes []float64, lastErrors []string) {
+	s.mutex.RLock()
+	defer s.mutex.RUnlock()
+
+	totalRequests = s.totalRequests
+	successfulRequests = s.successfulRequests
+	failedRequests = s.failedRequests
+	totalResponseTime = s.totalResponseTime
+
+	recentResponseTimes = make([]float64, 0, common.MaxResponseTimes)
+	for _, t := range s.recentResponseTimes {
+		if t > 0 {
+			recentResponseTimes = append(recentResponseTimes, t)
+		}
+	}
+
+	lastErrors = make([]string, 0, common.MaxErrors)
+	for _, e := range s.lastErrors {
+		if e != "" {
+			lastErrors = append(lastErrors, e)
+		}
+	}
+	return
+}
+
+func GetMemoryInfo() map[string]interface{} {
+	var m runtime.MemStats
+	runtime.ReadMemStats(&m)
+	return map[string]interface{}{
+		"total_alloc": m.TotalAlloc,
+		"heap_alloc":  m.HeapAlloc,
+		"heap_inuse":  m.HeapInuse,
+		"goroutines":  runtime.NumGoroutine(),
+	}
+}