Return error when model price/ratio unset

#3079
Change ModelPriceHelperPerCall to return (PriceData, error) and stop silently falling back to a default price. If a model price is not configured the helper now returns an error (unless the user has AcceptUnsetRatioModel enabled and a ratio exists). Propagate this error to callers: Midjourney handlers now return a MidjourneyResponse with Code 4 and the error message, and task submission returns a wrapped task error with HTTP 400. Also extract remix video_id in ResolveOriginTask for remix actions. This enforces explicit model price/ratio configuration and surfaces configuration issues to clients.

relay/relay_task.go

@@ -41,6 +41,8 @@ func ResolveOriginTask(c *gin.Context, info *relaycommon.RelayInfo) *dto.TaskErr
 	if strings.Contains(path, "/v1/videos/") && strings.HasSuffix(path, "/remix") {
 		info.Action = constant.TaskActionRemix
 	}
+
+	// 提取 remix 任务的 video_id
 	if info.Action == constant.TaskActionRemix {
 		videoID := c.Param("video_id")
 		if strings.TrimSpace(videoID) == "" {
@@ -176,7 +178,11 @@ func RelayTaskSubmit(c *gin.Context, info *relaycommon.RelayInfo) (*TaskSubmitRe
 
 	// 4. 价格计算：基础模型价格
 	info.OriginModelName = modelName
-	info.PriceData = helper.ModelPriceHelperPerCall(c, info)
+	priceData, err := helper.ModelPriceHelperPerCall(c, info)
+	if err != nil {
+		return nil, service.TaskErrorWrapper(err, "model_price_error", http.StatusBadRequest)
+	}
+	info.PriceData = priceData
 
 	// 5. 计费估算：让适配器根据用户请求提供 OtherRatios（时长、分辨率等）
 	//    必须在 ModelPriceHelperPerCall 之后调用（它会重建 PriceData）。