Mobile: markdown table scrollbar sits on top of the table rows, so swiping scrolls the wrong way

**Describe the bug**

On iOS, a markdown table in a message scrolls horizontally, but its scrollbar is not drawn at the bottom edge of the table — it sits roughly one to three rows above the bottom, on top of the table content.

Because the scrollbar overlays the area you would naturally drag, a horizontal swipe that starts there grabs the scrollbar thumb instead of the table, and the table jumps in the opposite direction from the intended drag. You have to place your finger carefully around the scrollbar to scroll the table normally.

**Steps to reproduce**

1. On iOS, open a channel containing a message with a markdown table wider than the screen.
2. Swipe horizontally across the lower rows of the table.
3. The touch lands on the scrollbar and the table moves the wrong way.

**Expected behavior**

The scrollbar sits at the bottom edge of the table and does not sit on top of table rows. Dragging anywhere on the table scrolls it in the direction of the drag.

**Version and platform**

- Buzz version: iOS app 0.11.0 (current App Store build)
- OS: iOS

**Logs / additional context**

No duplicate found. Issue 5313 also concerns markdown tables, but it is about desktop thread-panel cells clipping their text, not about scrollbar placement or touch handling on iOS.