Android-only update.
Changes:
- Added a spectrum/waterfall zoom slider to the Android client.
- Portrait: horizontal zoom slider at the bottom of the screen.
- Landscape: vertical zoom slider at the right edge.
- Slider and pinch zoom stay synchronized.
- Zoom level is persisted across app restarts and orientation changes.
Assets:
- Android debug APK for direct testing.
- Unsigned release APK for signing/repackaging.
- Android source snapshot for this release.