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/utils/shareChannels.ts

@@ -1,4 +1,4 @@
-import { resolveMindSpaceHomeUrl } from './publicUrl';
+import { resolveMindSpaceHomeUrl, resolveMindSpacePagePublicViewUrl, resolvePublicPageUrl } from './publicUrl';
 import type { MindSpacePage } from '../types';
 
 export type SharePayload = {
@@ -58,8 +58,8 @@ export const SHARE_CHANNELS: ShareChannel[] = [
 
 export function buildPageSharePayload(page: MindSpacePage, pagePublicUrl?: string): SharePayload {
   const publicUrl = pagePublicUrl
-    ? new URL(pagePublicUrl, window.location.origin).toString()
-    : window.location.href;
+    ? resolvePublicPageUrl(pagePublicUrl)
+    : resolveMindSpacePagePublicViewUrl(page) ?? window.location.href;
   return {
     title: page.title || '我的 MindSpace 页面',
     url: publicUrl,