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/analytics/productAnalytics.ts

@@ -54,6 +54,7 @@ export function normalizeProductRoute(pathname: string, search = '') {
 export function resolveProductRouteName(pathname: string) {
   if (pathname === '/') return 'chat';
   if (pathname === '/space') return 'mindspace_home';
+  if (pathname === '/space/achievements') return 'mindspace_achievements';
   if (pathname.startsWith('/space/page/')) return 'mindspace_page';
   if (pathname.startsWith('/feedback/')) return 'feedback_detail';
   if (pathname === '/feedback') return 'feedback';