refactor: 重构并优化项目多项功能

1. 调整CORS中间件挂载位置，重构CORS处理逻辑
2. 重写IP获取逻辑，增加私有网络IP信任校验
3. 优化日志中间件，移除/health接口单独日志逻辑
4. 改进API密钥未配置时的提示信息
5. 重构volcano TTS调用，新增voice参数支持
6. 优化请求体过大错误处理
7. 完善统计服务，修复环形缓冲区遍历逻辑，新增去重错误日志功能

middleware/logger.go

@@ -18,13 +18,6 @@ func (rec *statusRecorder) WriteHeader(code int) {
 
 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)