fix(canvas): keep uploaded resources in asset library (#388)

web/src/types/timeline.ts

@@ -68,6 +68,8 @@ export type TimelineClipKind = "video" | "audio" | "subtitle" | "text" | "image"
 export type TimelineDirectMedia = {
     /** 源素材 id（本地资产 id / 上传文件 id），用于生成时间线内唯一 nodeId 前缀 */
     id: string;
+    /** 远端素材库记录；本地上传成功后必须存在。 */
+    assetId?: string;
     kind: "video" | "audio" | "image" | "text";
     title: string;
     storageKey?: string;