Let a behavior hear the end of an animation it played itself

A behavior that played an animation on the parent of its owner never
heard it finish. On animation finished listened to the owner and to
what stands below it, and the parent stands above.

- Play animation notes on the player which behavior asked for it.
- On animation finished hears, as before, every animation on the
  owner or below it, and now also every animation the behavior
  played itself, on whatever object. Its output object names that
  object.
- Two behaviors that both played the same animation on the same
  object each hear its end once.
- A behavior that is called by Run behavior or heard by an On node
  counts as the behavior it sits in.
- The description of the node and the engine prompt say so.

Tests:
- Gate on melektaus-atx: 218 files, 3392 tests, CHECK EXIT 0.
- Two new unit tests: the behavior hears the animation on the parent
  of its owner while a bystander does not, and two starters hear it
  once each.
- Both counter-probes bite.
- e2e 6,17-26 on melektaus-atx: 480 checks, all pass.
- No new e2e check, and nothing was looked at in the browser. The
  rule for called and heard behaviors has no test of its own.

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

src/core/model/animation.ts

@@ -548,6 +548,11 @@ export interface AnimationPlayer {
   /** Seconds a `once-reset` pass takes to blend back to its starting values when its frames run out. */
   blendOut?: number;
   fade?: AnimationFade;
+  /**
+   * Who asked for it – the behaviors that played it, which hear its end wherever the object stands.
+   * Opaque here: the runtime hands in its behavior entities.
+   */
+  startedBy?: object[];
 }
 
 /**
@@ -596,7 +601,8 @@ let startCount = 0;
  * when a `once-reset` pass already ran out, starts over. `blendOutSeconds` is the fade at the end of
  * a `once-reset` pass. `restart` starts a known one over from its first frame in any case – blended in
  * from where it stands when `blendSeconds` is set – and keeps its starting values, so a relative row
- * does not add up.
+ * does not add up. `startedBy` is noted on the player next to whoever asked before, so each of them
+ * hears it finish.
  */
 export function playAnimation(
   holder: PlayerHolder,
@@ -604,12 +610,15 @@ export function playAnimation(
   blendSeconds = 0,
   blendOutSeconds = 0,
   restart = false,
+  startedBy?: object,
 ): void {
   const players = (holder.animations ??= []);
   const known = players.find((p) => p.animationId === animationId);
   const blend = blendSeconds > 0 ? { seconds: blendSeconds, elapsed: 0 } : undefined;
   const blendOut = blendOutSeconds > 0 ? blendOutSeconds : undefined;
   if (known) {
+    if (startedBy && !known.startedBy?.includes(startedBy))
+      known.startedBy = [...(known.startedBy ?? []), startedBy];
     const leads = players.every((p) => p.order <= known.order);
     const fade = known.fade;
     known.playing = true;
@@ -633,6 +642,7 @@ export function playAnimation(
     order: ++startCount,
     ...(blend && { blend }),
     ...(blendOut && { blendOut }),
+    ...(startedBy && { startedBy: [startedBy] }),
   });
 }