T11c motion: transitions, stagger, presence that folds, flip that glides, drag to reorder; motion keeps each row's identity

tasks/ch11-20.md

@@ -25,16 +25,19 @@
 - [x] RefreshIndicator → `motion::RefreshIndicator`
 - [x] TypingIndicator → `motion::TypingIndicator`
 
-## T11c Motion
+## T11c Motion · Presence & order — `src/motion`
+
+- [x] Transition — fade, slide, scale, collapse → `motion::Transition` fades, rises and slides; collapse is `layout::Collapsible`; scale is blocked: gpui 0.2.2 transforms only icons
+- [x] AnimatePresence → `motion::AnimatePresence`
+- [x] Motion → gpui's `with_animation`, timed by `motion::duration` and eased by the curves in `motion`
+- [x] Spring → `motion::spring`
+- [x] Stagger → `motion::Stagger`
+- [x] Reorder → `motion::Reorder`
+- [x] Flip → `motion::Flip`
+- [x] CountUp → `typography::AnimatedNumber`, counting up
+
+## T11d Motion · Effects
 
-- [ ] Transition — fade, slide, scale, collapse
-- [ ] AnimatePresence
-- [ ] Motion
-- [ ] Spring
-- [ ] Stagger
-- [ ] Reorder
-- [ ] Flip
-- [ ] CountUp → `typography::AnimatedNumber`
 - [ ] Marquee
 - [ ] Ripple
 - [ ] Confetti