Hold a running game, and let the editor run reach into containers

Pause is a sub-state of play, not a third mode: the toolbar button and
Ctrl+Enter stop ticking the world, the clock included. A held frame still
drops the input edges, so resuming does not fire a pause worth of keys in
one go.

The editor run missed the case it is most wanted for. hasEditorRun only
looked at the stored scene objects, so a behavior inside a placed
container never started one; the world now builds from resolveObjects and
writes back through objectRef, keeping the move as an instance edit
instead of baking the instance out.

Keys and clicks go to the run while the Game tab is on screen, where no
key means anything to the editor, and are handed back on leaving it -
held keys released, so nothing keeps walking unpressed.

tools/e2e/index.mjs

@@ -20,6 +20,7 @@ import { overflow } from './14-overflow.mjs';
 import { aspect } from './15-aspect.mjs';
 import { containerTab } from './16-container.mjs';
 import { editorRun } from './17-editor-run.mjs';
+import { pause } from './18-pause.mjs';
 
 export const STEPS = [
   hierarchy,
@@ -39,4 +40,5 @@ export const STEPS = [
   aspect,
   containerTab,
   editorRun,
+  pause,
 ];