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/service/admin_write.go

@@ -391,7 +391,6 @@ func (s *AdminWriteService) CreateModel(ctx context.Context, body map[string]any
 		Name:                defaultString(strings.TrimSpace(stringValue(body["name"])), modelID),
 		Alias:               alias,
 		Provider:            provider,
-		Enabled:             boolValueWithDefault(body["enabled"], true),
 		Ratios:              jsonArray(body["ratios"]),
 		Prices:              prices,
 		Resolutions:         resolutions,
@@ -440,13 +439,6 @@ func (s *AdminWriteService) UpdateModel(ctx context.Context, modelID string, bod
 			patch["provider"] = provider
 		}
 	}
-	// Only touch `enabled` when the caller explicitly sends a non-null value;
-	// mirrors Python models_store.update ("enabled" in fields and is not None).
-	// Without this guard a PATCH that omits the field would default it to false
-	// and silently disable the model.
-	if raw, ok := body["enabled"]; ok && raw != nil {
-		patch["enabled"] = boolValueWithDefault(raw, true)
-	}
 	if _, ok := body["ratios"]; ok {
 		patch["ratios"] = jsonArray(body["ratios"])
 	}