- Match View() and getItemAndLineAtY() row counts for empty items so
streaming-reasoning placeholders no longer offset hit-testing by one
row each (exposed when extension widgets like subagent-monitor shrink
the scrollback).
- Honor IsLineInRange's endCol=-1 'to end of line' sentinel in
HighlightLine and ExtractText so the start row of a multi-line drag
actually renders highlighted and is included in clipboard copies.
- Add regression tests for both invariants in scrolllist and selection.