feat(mindspace): 全部页面管理、级联删除与页面同步去重

支持全部页面分页/多选/删除/分享，删除时可选移除广场帖并清理工作区附件；修复并发同步重复创建页面，并补齐预览下载链接重写与 iframe 下载权限。

Co-authored-by: Cursor <cursoragent@cursor.com>

src/types.ts

@@ -619,6 +619,13 @@ export type MindSpacePage = {
   updatedAt: number;
 };
 
+export type MindSpacePagePlazaPostPreview = {
+  id: string;
+  title: string;
+  status: string;
+  publicationId: string;
+};
+
 export type MindSpacePageDeletePreview = {
   page: {
     id: string;
@@ -633,6 +640,7 @@ export type MindSpacePageDeletePreview = {
     viewCount: number;
   } | null;
   offlinePublicationCount: number;
+  plazaPosts: MindSpacePagePlazaPostPreview[];
   linkedAssets: Array<{
     id: string;
     displayName: string;
@@ -650,6 +658,7 @@ export type MindSpacePageDeleteResult = {
   pageId: string;
   title: string;
   offlinedPublicationCount: number;
+  hiddenPlazaPostCount: number;
   deletedAssetCount: number;
   freedBytes: number;
   clearedAgentJobCount: number;