Interaction · Pointer: resize, turn, band selection, and gpui's own drag

Resizable sizes a box from its right and bottom edges and a grip at
its corner, within its least and greatest size; the grip is a Tab stop
whose arrows resize a step. Rotatable turns an svg to its angle inside
a ring whose knob a drag moves, Shift snapping to 15 degrees, with the
arrows turning it a notch. SelectionArea selects items with a band
drawn on empty space, a press, Command or Shift to add, and a cursor
the arrows walk with Space to add or drop; Escape clears and
Command-A takes all. The gallery shows gpui's own drag and drop, drag
preview, double press and wheel zoom, with pointers for Sortable,
LongPress and PanZoom; pinch stays blocked, gpui 0.2.2 forwards no
magnify event.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tasks/ch31-43.md

@@ -217,21 +217,24 @@
 - [x] InlineHelp
 - [x] EmptyStateWithAction → `feedback::EmptyState`, whose `action` adds its buttons
 
-## T38 Interaction — `src/interaction`
+## T38a Interaction · Pointer — `src/interaction`
+
+- [x] Draggable — native `on_drag`
+- [x] Droppable / DropTarget — native `on_drop`, `drag_over`, `can_drop`
+- [x] DragOverlay / DragPreview — native drag view
+- [x] DragGhost → DragPreview (native)
+- [x] Sortable / SortableContext → `motion::Reorder`
+- [x] Resizable
+- [x] Rotatable — an svg: gpui 0.2.2 turns no other element
+- [x] Selectable / SelectionArea
+- [x] RubberBandSelection → `interaction::SelectionArea`
+- [x] LongPress → `primitives::Pressable`
+- [x] DoubleClick — native `ClickEvent::click_count`
+- [x] Gesture — prove: wheel zoom through `layout::Viewport`, two-finger swipe through `lists::SwipeableListItem`; pinch blocked, gpui 0.2.2 forwards no magnify event
+- [x] PanZoom → `layout::Viewport`
+
+## T38b Interaction · Keys, scroll and focus
 
-- [ ] Draggable — native `on_drag`
-- [ ] Droppable / DropTarget — native `on_drop`, `drag_over`
-- [ ] DragOverlay / DragPreview — native drag view
-- [ ] DragGhost → DragPreview (native)
-- [ ] Sortable / SortableContext
-- [ ] Resizable
-- [ ] Rotatable
-- [ ] Selectable / SelectionArea
-- [ ] RubberBandSelection → `interaction::SelectionArea`
-- [ ] LongPress → `primitives::Pressable`
-- [ ] DoubleClick — native `ClickEvent::click_count`
-- [ ] Gesture — prove: wheel zoom, pinch, two-finger swipe
-- [ ] PanZoom → `layout::Viewport`
 - [ ] Hotkeys / KeyBinding — native `actions!`, `bind_keys`, `key_context`
 - [ ] KeyChord — native multi-keystroke bindings
 - [ ] Undo / Redo Manager