The drag handle was attached only to the left sub-view of each row, so
grabbing the right half initiated no drag, and pointerdown on the branch
or project title raced the browser's text-selection start before
dnd-kit's activation threshold — often producing a text selection
instead of a drag.
Move dragHandleProps to the outer row wrapper, add userSelect: none to
the row styles, and tighten PointerSensor activation distance.
Add useWebElementScrollbar (for DOM elements) and useWebScrollViewScrollbar
(for RN ScrollView/FlatList) hooks that return renderable overlays, replacing
manual WebDesktopScrollbarOverlay wiring across all consumers. Apply the
themed scrollbar to the message input textarea. Tint the dark-mode scrollbar
handle to match the teal-tinted dark theme.
Closes#174
Mohamed Boudra