[Bug]: Integrated terminal text selection does not auto-scroll downward

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/desktop

Steps to reproduce

1. Open the integrated terminal.
2. Generate several screens of scrollable output, for example:
   for i in {1..500}; do echo "Test output line $i - safe dummy terminal text for scrolling"; done
3. Scroll somewhere into the terminal output.
4. Start selecting text near the top of the visible terminal area.
5. Keep the mouse button held and drag the pointer below the bottom of the terminal.
6. Observe that the terminal does not scroll downward.
7. Now start a selection near the bottom and drag the pointer above the top edge.
8. Observe that the terminal does scroll upward, but very slowly.

Expected behavior

Dragging a text selection beyond either the top or bottom edge of the terminal should automatically scroll in that direction at a usable speed.

The behaviour should be consistent in both directions.

Actual behavior

• Top-to-bottom selection: no downward auto-scroll.
• Bottom-to-top selection: upward auto-scroll works, but is very slow.
• Manual scrolling after making a selection works once the selection popup is dismissed.

Impact

Minor bug or occasional failure

Version or commit

No response

Environment

T3 Code V0.0.42, MacOS: Golden Gate 27.0, Input Device: trackpad and mouse

Logs or stack traces

Screenshots, recordings, or supporting files

Screen Recording 2026-09-16 at 16.27.11.mov

Workaround

Making smaller selections when selecting from top to bottom or resizing terminal window

Start in apps/desktop by reproducing the integrated terminal selection behavior described in the steps, then locate the terminal text-selection and auto-scroll entry points. Verify the fix by dragging selections beyond both the top and bottom edges and confirming scrolling works consistently at a usable speed.