fix: paginate the bookmarks and collections lists with Load more

Both lists fetched a single capped page (100 / 200) with no pager, so entries
past the cap were silently unreachable. Add a reusable LoadMore component that
seeds from the streamed first page (preserving the auth gate + inline error
handling) and fetches further offset-based pages on demand, and wire it into
the bookmarks and collections pages.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.127.1",
+  "version": "0.127.2",
   "private": true,
   "type": "module",
   "scripts": {