fix(studio): ignore keyframe re-drag during the optimistic-hold window

After a drop, the diamond is held at its dropped position (via effPct) until the
file round-trip lands, but `pct` passed to handlePointerDown still comes from
props (the pre-drop position). Re-grabbing the same keyframe in that window
would track the drag from a stale origin and commit against the wrong tween (or
no-op via the stale-cache guard). Skip starting a drag while a hold is pending;
it clears on the cache match (≤2s fallback). Click selection is unaffected.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-authored-by: Miguel Ángel <miguel07alm@protonmail.com>

Author: vanceingalls

packages/studio/src/player/components/TimelineClipDiamonds.tsx

@@ -124,6 +124,11 @@ export const TimelineClipDiamonds = memo(function TimelineClipDiamonds({
   const handlePointerDown = (e: React.PointerEvent, pct: number) => {
     if (e.button !== 0) return;
     e.stopPropagation();
+    // Ignore a new drag while a prior drop is still settling: `pct` comes from
+    // props (the pre-drop position) but the diamond is held at its dropped spot
+    // via effPct(), so a re-grab would track from a stale origin and commit
+    // against the wrong tween. The hold clears on the cache round-trip (≤2s).
+    if (pendingRef.current) return;
     // Select the element up front so its GSAP session loads during the drag and
     // the commit (which resolves the animation from the selection) isn't a no-op.
     onPickForDrag?.();