fix: expand CLOUD_MASK_URLS + ensure both orientations for non-square devices

- CLOUD_MASK_URLS was missing all non-square resolutions — users with
  1280x480 (and other rotatable devices) got "No cloud URL" when trying
  to download portrait masks (fixes issue #95)
- Added all resolutions with bundled archives (480x1280, 720x1600, etc.)
- Added billboard devices (640x172, 960x320, 1920x440) as cloud-only entries
- ensure_all() now extracts web previews + masks for both landscape and
  portrait orientations for non-square devices

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>