fix(studio): close the review findings that survived the stack

Selector reads now go through one inverse of `idSelector`. Every writer emits
`[id="01-hook-hero"]` for an id a `#id` selector can't address, but the readers
still matched `#id` only, so the post-commit keyframe-cache refresh, the AST
load and the remove-all-keyframes clear all silently skipped exactly the ids
`idSelector` was added to support.

A keyframe merged from two tweens with different eases kept whichever ease
iterated last. Readers that don't check `easeAmbiguous` showed a curve from a
different animation than an edit would target, so the ambiguous flag now clears
`ease` instead of leaving an arbitrary one behind.

One tolerance for "the playhead is on this keyframe". The motion-path drag used
0.05% while the toolbar and the playhead apply used 1%, so a drag that landed a
fraction of a percent off an authored waypoint skipped the update-point branch
and appended a near-duplicate. `buildTemporalArcKeyframes` now owns the
invariant and replaces any keyframe inside the tolerance, rather than trusting
each caller's own pre-check.

The pending-retime bookkeeping matches on keyframe identity, not just on
"something is near that percentage" — an evenly spaced row cleared the entry off
an unrelated sibling. The neighbour clamp composes pending destinations in
before sorting, so a second drag can't cross a neighbour that already moved.

Also: `keyframeCache`/`gsapAnimations` setters return the same state for a write
that changes nothing (every no-op re-rendered every subscriber), the auto-expand
set drops clips that left the source so an undo/paste under the same id expands
again, `invalidateGsapCache` has a stable identity instead of re-creating the
whole timeline edit context each render, the studio test hook deletes its window
key rather than leaving it enumerable as undefined, and the past-last-row
extrapolation documents why it uses TRACK_H where the pre-first-row branch uses
row 0's own height.

Covers `idFromSelector` round-trips, the insert boundary band across plain,
expanded and unusable row heights, and the collapsed selection key for a
colon-bearing element id.

packages/studio/src/hooks/useEnableKeyframes.ts

@@ -15,6 +15,7 @@ import { fetchParsedAnimations, getAnimationsForElement } from "./useGsapTweenCa
 import {
   selectorFromSelection,
   computeElementPercentage,
+  KEYFRAME_PCT_MATCH,
   isInstantHold,
   resolveEditableTweenDuration,
 } from "./gsapShared";
@@ -302,7 +303,9 @@ async function applyKeyframeAtPlayhead(
   }
   const pct =
     start === null ? computeElementPercentage(t, sel) : absoluteToPercentage(t, start, duration);
-  const existing = kfAnim.keyframes?.keyframes.find((k) => Math.abs(k.percentage - pct) <= 1);
+  const existing = kfAnim.keyframes?.keyframes.find(
+    (k) => Math.abs(k.percentage - pct) <= KEYFRAME_PCT_MATCH,
+  );
   if (existing) {
     session.handleGsapRemoveKeyframe(kfAnim.id, existing.percentage);
     return;
@@ -406,7 +409,7 @@ export async function applyArcKeyframeAtPlayhead(
   const nodes = arcAnim.keyframes?.keyframes ?? [];
   const playheadPercentage = absoluteToPercentage(t, start, duration);
   const timedNodeIndex = nodes.findIndex(
-    (node) => Math.abs(node.percentage - playheadPercentage) <= 1,
+    (node) => Math.abs(node.percentage - playheadPercentage) <= KEYFRAME_PCT_MATCH,
   );
   if (timedNodeIndex !== -1) {
     if (timedNodeIndex > 0 && timedNodeIndex < nodes.length - 1) {