fix: reader loads the full chapter list for prev/next and the dropdown

The reader fetched only the first 200 chapters, so a deep chapter (#250) fell
outside the window and its prev/next chevrons resolved to null — a dead end —
and the chapter dropdown was truncated. Add listAllChapters, which pages
through the API's 200-row cap, and use it in the reader loader.

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

frontend/package.json

@@ -1,6 +1,6 @@
 {
   "name": "mangalord-frontend",
-  "version": "0.127.0",
+  "version": "0.127.1",
   "private": true,
   "type": "module",
   "scripts": {