Play switches to scene tab; graph tab strictly follows selection

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

README.md

@@ -54,8 +54,11 @@ shown on the node and editable in the inspector.
   (types are checked; a data input holds one link and is replaced), drag nodes, right-click a
   node or port to delete/disconnect, `Delete` removes the selected node, wheel zooms, dragging
   the empty canvas pans. Everything is undoable.
-- **Live view**: while playing with the Graph tab open, the exec edges and nodes that just ran
-  light up – the same canvas draws editor and game, so this costs nothing extra.
+- **Selection-bound**: the Graph tab shows the behavior the current selection refers to
+  (asset, placed object or node); with nothing or a non-behavior selected it is empty.
+- **Live view**: Play always switches to the Scene tab; switch back to Graph while playing and
+  the exec edges and nodes that just ran light up – the same canvas draws editor and game, so
+  this costs nothing extra.
 - **Runtime**: `BehaviorSystem` creates one `GraphInterpreter` per behavior entity; graphs only
   touch world entities. A runaway loop throws after 1000 steps and stops play with a notice.