fix: 修复请求体过大处理和冗余代码问题

1. 修复OpenAI TTS接口的请求体过大错误提示，返回正确的状态码和提示信息
2. 删除volcano适配器中无用的空循环扫描代码
3. 修正constants.go的包声明重复空格问题

controller/tts.go

@@ -58,10 +58,11 @@ func OpenaiTTSHandler(w http.ResponseWriter, r *http.Request) {
 	r.Body = http.MaxBytesReader(w, r.Body, common.MaxRequestBodySize)
 	body, err := io.ReadAll(r.Body)
 	if err != nil {
-		if strings.Contains(err.Error(), "request body too large") {
-			return
-		}
-		http.Error(w, "Failed to read request body", http.StatusBadRequest)
+	if strings.Contains(err.Error(), "request body too large") {
+		http.Error(w, fmt.Sprintf("Request body too large (max %d bytes)", common.MaxRequestBodySize), http.StatusRequestEntityTooLarge)
+		return
+	}
+	http.Error(w, "Failed to read request body", http.StatusBadRequest)
 		return
 	}