Behavior lifecycle: On enable, On disable and On destroy events (#42)

Order per instance: On start -> On enable -> On update ... -> On disable
-> On destroy. On enable fires right after On start and whenever the
behavior comes back on (itself and its parents); On disable in the frame
it goes off, the instance stays frozen. On destroy fires when the entity
leaves the world (Destroy node, child of a destroyed object) and when the
world is torn down on stop/restart, preceded by On disable if still on.
A new On start node added while playing still does not fire for a
running instance (kept as is, documented in the wiki).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tests/core/node-catalog.test.ts

@@ -677,7 +677,10 @@ function eqNamesakes(): Record<string, Value> {
 const EVENT_NODES: Record<string, string> = {
   BehaviorStart: 'nested-behavior.test.ts',
   OnStart: 'graph.test.ts',
+  OnEnable: 'behavior-events.test.ts',
   OnUpdate: 'graph.test.ts',
+  OnDisable: 'behavior-events.test.ts',
+  OnDestroy: 'behavior-events.test.ts',
   OnKeyDown: 'behavior-events.test.ts',
   OnKeyUp: 'behavior-events.test.ts',
   OnKeyHeld: 'behavior-events.test.ts',