fix(studio): address family B timeline review findings

- revert diamond selection when a rejected retime leaves the source in place
- clear project-local ease focus and expansion on player store reset
- share one static-position-hold predicate across the tween cache
- invalidate the GSAP cache even when a group timing rewrite throws
- stamp each lane keyframe's ease from its own source tween
- memoize property lanes and row offsets so memo'd diamond lanes hold
- use the editable tween duration for drag position commits
- restore the pre-t=0 pad in the all-collapsed content origin
- clamp the drag ghost and drop placeholder to the collapsed clip height
- aria-expanded on the layer disclosure, aria-pressed plus state-specific
  labels on the keyframe toggle, 24px chevron targets, focus-visible parity

packages/studio/src/hooks/useGsapTweenCache.ts

@@ -330,9 +330,14 @@ export function useGsapAnimationsForElement(
   // fallow-ignore-next-line complexity
   useEffect(() => {
     if (!elementId) return;
-    // No property-group filter: ungrouped tweens are recorded here as well.
+    // Same admission rule as the keyframe cache below (hold skip included) and
+    // no property-group filter: the two stores must agree, or a hold draws an
+    // expanded property lane with no collapsed diamond behind it and an
+    // ungrouped tween draws diamonds with no lane source.
     const sourceAnimations = animations.filter(
-      (animation) => animation.keyframes || synthesizeFlatTweenKeyframes(animation),
+      (animation) =>
+        !isStaticPositionHold(animation) &&
+        (animation.keyframes || synthesizeFlatTweenKeyframes(animation)),
     );
     if (sourceAnimations.length > 0)
       writeGsapAnimationsForElement(sourceFile, elementId, sourceAnimations);