Mobile: floating "Latest" jump-to-bottom button overlaps last message(s)

**App version:** 0.8.0
**Platform:** Mobile (Android)

**Bug:** When new messages arrive in a channel, the floating "↓ Latest" jump-to-bottom pill renders directly on top of the last 1-2 lines of the most recent message, obscuring the content instead of appearing below/beside it near the composer.

**Expected:** The pill should not overlap message content — either message list should account for its height (extra bottom padding) or it should float clear of the text.

**Repro:** Send/receive a message long enough that the last lines sit near the composer while the "Latest" pill is showing (e.g. after scrolling up and new messages arrive).

Reproduce this on Android in a mobile channel by scrolling up until new messages show the “Latest” pill near the composer. Trace the message list and floating pill positioning, then verify that long final messages remain fully readable while the pill is visible.

Written by the indexing model from the issue text.