Search results can leave a floating horizontal scrollbar artifact

Summary

Search results could leave stale horizontal scrollbar pixels floating inside the blank area to the right of the populated columns after list movement, redraw, or scrolling.

Outcome

• Search status overlay bounds are constrained to the list client area.
• Search result list moves avoid copying old pixels from the previous frame.
• Search result rows repaint through the visible client width so the blank area to the right of the columns does not preserve stale scrollbar artifacts.

Validation

• python -m emule_workspace validate
• python -m emule_workspace build app --variant main --config Debug --platform x64 --build-output-mode ErrorsOnly