Android: opening a channel does not scroll to the newest message

## Summary

On Android, opening a channel does not land at the newest message. The view restores partway up the history, so you have to scroll all the way down to see what has just been said.

## Steps to reproduce

1. Open a channel and read to the bottom.
2. Navigate away (to another channel or out of the app).
3. Come back to the first channel.

## Expected

The channel opens at the bottom, showing the newest message — as chat apps generally do.

## Actual

The view opens somewhere up the history and stays there. Reaching the latest message requires manually scrolling to the bottom every time.

## Note

Jumping to the newest message on open would be the expected default. If preserving the last read position is deliberate, an unread divider plus a visible "jump to latest" control would make it discoverable — at the moment there is no indication that newer messages exist below.

Happy to provide device model, Android version and app build number if that helps.