feat(task): add model redirection, per-call billing, and multipart retry fix for async tasks

1. Async task model redirection (aligned with sync tasks):
   - Integrate ModelMappedHelper in RelayTaskSubmit after model name
     determination, populating OriginModelName / UpstreamModelName on RelayInfo.
   - All task adaptors now send UpstreamModelName to upstream providers:
     - Gemini & Vertex: BuildRequestURL uses UpstreamModelName.
     - Doubao & Ali: BuildRequestBody conditionally overwrites body.Model.
     - Vidu, Kling, Hailuo, Jimeng: convertToRequestPayload accepts RelayInfo
       and unconditionally uses info.UpstreamModelName.
     - Sora: BuildRequestBody parses JSON and multipart bodies to replace
       the "model" field with UpstreamModelName.
   - Frontend log visibility: LogTaskConsumption and taskBillingOther now
     emit is_model_mapped / upstream_model_name in the "other" JSON field.
   - Billing safety: RecalculateTaskQuotaByTokens reads model name from
     BillingContext.OriginModelName (via taskModelName) instead of
     task.Data["model"], preventing billing leaks from upstream model names.

2. Per-call billing (TaskPricePatches lifecycle):
   - Rename TaskBillingContext.ModelName → OriginModelName; add PerCallBilling
     bool field, populated from TaskPricePatches at submission time.
   - settleTaskBillingOnComplete short-circuits when PerCallBilling is true,
     skipping both adaptor adjustments and token-based recalculation.
   - Remove ModelName from TaskSubmitResult; use relayInfo.OriginModelName
     consistently in controller/relay.go for billing context and logging.

3. Multipart retry boundary mismatch fix:
   - Root cause: after Sora (or OpenAI audio) rebuilds a multipart body with a
     new boundary and overwrites c.Request.Header["Content-Type"], subsequent
     calls to ParseMultipartFormReusable on retry would parse the cached
     original body with the wrong boundary, causing "NextPart: EOF".
   - Fix: ParseMultipartFormReusable now caches the original Content-Type in
     gin context key "_original_multipart_ct" on first call and reuses it for
     all subsequent parses, making multipart parsing retry-safe globally.
   - Sora adaptor reverted to the standard pattern (direct header set/get),
     which is now safe thanks to the root fix.

4. Tests:
   - task_billing_test.go: update makeTask to use OriginModelName; add
     PerCallBilling settlement tests (skip adaptor adjust, skip token recalc);
     add non-per-call adaptor adjustment test with refund verification.

controller/task.go

@@ -9,6 +9,7 @@ import (
 	"github.com/QuantumNous/new-api/model"
 	"github.com/QuantumNous/new-api/relay"
 	"github.com/QuantumNous/new-api/service"
+	"github.com/QuantumNous/new-api/types"
 
 	"github.com/gin-gonic/gin"
 )
@@ -37,7 +38,7 @@ func GetAllTask(c *gin.Context) {
 	items := model.TaskGetAllTasks(pageInfo.GetStartIdx(), pageInfo.GetPageSize(), queryParams)
 	total := model.TaskCountAllTasks(queryParams)
 	pageInfo.SetTotal(int(total))
-	pageInfo.SetItems(tasksToDto(items))
+	pageInfo.SetItems(tasksToDto(items, true))
 	common.ApiSuccess(c, pageInfo)
 }
 
@@ -61,13 +62,32 @@ func GetUserTask(c *gin.Context) {
 	items := model.TaskGetAllUserTask(userId, pageInfo.GetStartIdx(), pageInfo.GetPageSize(), queryParams)
 	total := model.TaskCountAllUserTask(userId, queryParams)
 	pageInfo.SetTotal(int(total))
-	pageInfo.SetItems(tasksToDto(items))
+	pageInfo.SetItems(tasksToDto(items, false))
 	common.ApiSuccess(c, pageInfo)
 }
 
-func tasksToDto(tasks []*model.Task) []*dto.TaskDto {
+func tasksToDto(tasks []*model.Task, fillUser bool) []*dto.TaskDto {
+	var userIdMap map[int]*model.UserBase
+	if fillUser {
+		userIdMap = make(map[int]*model.UserBase)
+		userIds := types.NewSet[int]()
+		for _, task := range tasks {
+			userIds.Add(task.UserId)
+		}
+		for _, userId := range userIds.Items() {
+			cacheUser, err := model.GetUserCache(userId)
+			if err == nil {
+				userIdMap[userId] = cacheUser
+			}
+		}
+	}
 	result := make([]*dto.TaskDto, len(tasks))
 	for i, task := range tasks {
+		if fillUser {
+			if user, ok := userIdMap[task.UserId]; ok {
+				task.Username = user.Username
+			}
+		}
 		result[i] = relay.TaskModel2Dto(task)
 	}
 	return result