NovelNotifier 1.2.1

No feature changes — this release re-signs the app with a proper release key (v1.2 and earlier were signed with a debug key from the project's earliest days).

If you installed v1.2 or earlier: this update will not install over it — please:

1. In the app: Settings → Back up library (save the zip somewhere safe)
2. Uninstall the old app
3. Install this APK
4. Settings → Restore from backup, then log in again

Your lists, chapter caches, covers, and settings all come back from the backup; only the login session needs redoing. New installs: ignore all of the above.

Full changelog: v1.2...v1.2.1