feat(model): 同步 vivid 最新变更 — 去模型开关,配价即上架

对齐 vivid a338edb / 7fb5c57 / 4f454b6:
- model_configs.enabled 列删除:上架唯一门槛 = 绑定了启用渠道 + 全部档位
  有价(视频另需时长有价)。/v1/models、/api/models、video-presets、
  managed-models 全部改按 sellable 透出
- 保存渠道即全量同步上游模型(消失解绑/孤儿删除/失败告警不删库)
- v1 job 持久化 upstream jobId,重启后维护循环按 jobId 续等不丢单

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

backend/internal/http/handler/channel_admin.go

@@ -38,7 +38,7 @@ func (h *ChannelAdminHandler) Save(c *gin.Context) {
 		return
 	}
 	body.BaseURL = strings.TrimSpace(body.BaseURL)
-	ch, err := h.channels.Save(c.Request.Context(), body)
+	ch, warning, err := h.channels.Save(c.Request.Context(), body)
 	if err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
 			c.JSON(http.StatusNotFound, gin.H{"detail": "channel not found"})
@@ -47,7 +47,7 @@ func (h *ChannelAdminHandler) Save(c *gin.Context) {
 		c.JSON(http.StatusBadRequest, gin.H{"detail": err.Error()})
 		return
 	}
-	c.JSON(http.StatusOK, gin.H{"ok": true, "id": ch.ID})
+	c.JSON(http.StatusOK, gin.H{"ok": true, "id": ch.ID, "warning": warning})
 }
 
 func (h *ChannelAdminHandler) Delete(c *gin.Context) {