Fix Video Player Behavior on Screen Lock for iOS and Android

[kdroidFilter]

This PR addresses inconsistent behavior when locking the screen during video playback across iOS and Android platforms. Previously, on Android, videos would continue playing when the screen was locked, while on iOS, videos would pause but the isPlaying state would incorrectly remain true.

Changes Made

iOS Implementation

• Added notification observers for app lifecycle events:
  • UIApplicationDidEnterBackgroundNotification (screen lock)
  • UIApplicationWillEnterForegroundNotification (screen unlock)
• When the screen is locked:
  • Store the current playing state
  • Update isPlaying state to match the actual player state
• When the screen is unlocked:
  • Resume playback if the video was playing before locking
  • Properly update the isPlaying state

Android Implementation

• Added a BroadcastReceiver to listen for screen events:
  • ACTION_SCREEN_OFF (screen lock)
  • ACTION_SCREEN_ON (screen unlock)
• When the screen is locked:
  • Store the current playing state
  • Pause playback if the video was playing
• When the screen is unlocked:
  • Resume playback if the video was playing before locking
• Properly register/unregister the receiver to prevent memory leaks

Benefits

• Consistent behavior across platforms: videos pause when the screen is locked and resume when unlocked
• Accurate isPlaying state that correctly reflects the actual playback state
• Improved user experience with predictable video behavior
• Proper resource management to prevent memory leaks

This PR resolves the issue where playerState.isPlaying would return true on iOS even when the video was actually paused after screen lock. #75