fix: import legacy projects without wrapper folder

hub/src/deployment/legacyProjectImport.ts

@@ -81,7 +81,7 @@ export async function importLegacyProjects(input: {
       sourceRelativePath: entry.sourceRelativePath,
     };
     await writeState(input.stateFile, { version: 1, projects });
-    const folderId = await ensureFolderPath(input.prisma, input.organizationId, ["旧教学资产", ...entry.folderPath]);
+    const folderId = await ensureFolderPath(input.prisma, input.organizationId, entry.folderPath);
     input.onProgress?.(`import ${entry.legacyId}: ${entry.name}`);
     const created = await createProjectFromOrgAdmin(input.prisma, {
       organizationId: input.organizationId,
@@ -123,7 +123,7 @@ async function ensureFolderPath(
   prisma: PrismaClient,
   organizationId: string,
   parts: readonly string[],
-): Promise<string> {
+): Promise<string | undefined> {
   let parentId: string | undefined;
   for (const name of parts) {
     const existing = await prisma.folder.findFirst({
@@ -141,7 +141,6 @@ async function ensureFolderPath(
     });
     parentId = created.id;
   }
-  if (parentId === undefined) throw new Error("legacy import folder path is empty");
   return parentId;
 }