[iOS] Abnormal blank space between message content and action bar in task conversation

## Bug Description

On the iOS app, some messages in the task conversation view display an abnormally large gap between the message content and the action bar (forward, copy, timestamp). The gap is visually prominent and inconsistent with messages that render correctly. This is an intermittent issue — not every task is affected, and not every message within an affected task shows the problem.

## Steps to Reproduce

1. Open any task conversation on the iOS app
2. Scroll through the messages
3. Observe that some messages have a large unexpected blank space between the message content area and the action bar (forward icon / copy icon / timestamp)

Note: the issue does not appear on every message. It appears intermittently within the same task and across different tasks.

## Expected Behavior

The action bar (forward, copy, timestamp) should appear directly below the message content with consistent and appropriate spacing, matching the layout of messages that render correctly.

## Actual Behavior

An abnormally large blank area appears between the message content and the action bar on affected messages. The gap takes up significant vertical space and makes the message list feel broken and inconsistent.

## Reproducibility

Intermittent — not every task or every message is affected. Observed in the same task across multiple messages.

## Impact

The inconsistent layout disrupts the reading flow and makes the UI appear broken. Users may think content is missing in the blank area.

## Environment

- Platform: iOS 26.5 (iPhone 17)
- Mobile app version: 0.1.41
- Component: Task conversation message list — message action bar

Start by reproducing the gap in the iOS task conversation message list, comparing affected and correctly rendered messages around the message action bar. Trace the layout from the task conversation view and verify that the action bar sits directly below message content with consistent spacing across messages and tasks.

Written by the indexing model from the issue text.