Force landscape orientation in player - #113

What Changed

This updates the player so playback opens in landscape mode instead of portrait on mobile/tablet devices.

The player now:

• switches the host activity to SCREEN_ORIENTATION_SENSOR_LANDSCAPE while the player screen is visible
• allows auto-rotation between the two landscape directions
• restores the previous activity orientation when the player is closed

Why

Movies and TV shows are primarily consumed in landscape, but the app was opening the player in portrait when the device itself was upright. That made the initial playback experience feel wrong and inconsistent.

Root Cause

MainActivity uses sensor-based orientation on phones and tablets, so when the player opened, it inherited the device's current portrait orientation instead of enforcing a playback-friendly landscape mode.

Impact

• player opens in landscape for video playback
• better viewing experience for movies and episodes
• normal app orientation behavior resumes after exiting the player

Validation

• built and verified with:
  • ./gradlew :app:compilePlayDebugKotlin :app:compileSideloadDebugKotlin