TMIY

Updates the app to target Android 16, per Google Play requirements. Also fixes unnecessary photo/video permission requests, a PDF viewer native-library rejection (now uses Android's built-in renderer), content hidden behind the gesture bar/taskbar on tablets, and cut-off session descriptions.

What to test: navigation & playback; splash/session screens on Android 15/16 (nothing hidden behind status/nav bar); PDF viewer (swipe, zoom, pan); session list last item + descriptions not cut off.