feat(mindspace): add achievements showcase with paginated management

Ship the M成果 page with list/delete UX, fix deletePage for incomplete page records, route /space/achievements, and add M成果 under the WeChat M空间 menu.

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

src/dev/mindspacePreviewData.ts

@@ -111,6 +111,8 @@ export const PREVIEW_PAGES: MindSpacePage[] = [
     currentVersionId: 'page-1-v2',
     versionNo: 2,
     contentFormat: 'markdown',
+    viewCount: 86,
+    clickCount: 5,
     createdAt: Date.now() - 172_800_000,
     updatedAt: Date.now() - 43_200_000,
   },
@@ -130,6 +132,8 @@ export const PREVIEW_PAGES: MindSpacePage[] = [
     currentVersionId: 'page-2-v1',
     versionNo: 1,
     contentFormat: 'html',
+    viewCount: 12,
+    clickCount: 2,
     createdAt: Date.now() - 259_200_000,
     updatedAt: Date.now() - 86_400_000,
   },