feat: refactor request body handling to use BodyStorage for improved efficiency

relay/gemini_handler.go

@@ -138,11 +138,11 @@ func GeminiHelper(c *gin.Context, info *relaycommon.RelayInfo) (newAPIError *typ
 
 	var requestBody io.Reader
 	if model_setting.GetGlobalSettings().PassThroughRequestEnabled || info.ChannelSetting.PassThroughBodyEnabled {
-		body, err := common.GetRequestBody(c)
+		storage, err := common.GetBodyStorage(c)
 		if err != nil {
 			return types.NewErrorWithStatusCode(err, types.ErrorCodeReadRequestBodyFailed, http.StatusBadRequest, types.ErrOptionWithSkipRetry())
 		}
-		requestBody = bytes.NewReader(body)
+		requestBody = common.ReaderOnly(storage)
 	} else {
 		// 使用 ConvertGeminiRequest 转换请求格式
 		convertedRequest, err := adaptor.ConvertGeminiRequest(c, info, request)