NCarousel

- Add: Optional Wi‑Fi-only (unmetered) network for automatic wallpaper downloads. - Change: Fit image mode fills letterbox edges with a soft blurred cover instead of black bars. - Change: Library pull-to-refresh reloads the current wallpaper EXIF highlight (full list sync stays on Home / empty-state button). - Fix: Quoted versionName literal for F-Droid Tags checkupdates (avoids versionName picking up the git tag “v…” prefix).