A step opens a tab the way a person has to, through the menu when it is hidden

CI run 35 was red: the suite died after step 15 with `widget with text
"Container" not found`. Nothing in the editor broke — the tenth tab (#73) pushed
Container behind the `»` button at the test window's 1280 px, exactly the case
#84 was built for, and three steps still clicked the tab name directly.

openTab(t, tab) in tools/e2e/lib/scaffold.mjs asks tabRow() whether the tab is
hidden and goes through the menu when it is, so the fix lives in one place rather
than in every step that opens a tab. The LABELS record moves there as TAB_LABELS,
since both the helper and 14-overflow need it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tools/e2e/14-overflow.mjs

@@ -1,3 +1,5 @@
+import { TAB_LABELS } from './lib/scaffold.mjs';
+
 /**
  * Labels must be shortened to fit their control, not written past it. Runs last because it renames
  * assets to absurd lengths to provoke the case.
@@ -6,20 +8,6 @@
 /** A name far wider than any 200 px picker, so a control that does not truncate must spill. */
 const LONG_NAME = 'Player movement with jumping and coyote time';
 
-/** What the tab buttons read, to find one in the overflow menu. */
-const LABELS = {
-  scene: 'Scene',
-  game: 'Game',
-  graph: 'Behavior',
-  statemachine: 'State machine',
-  shader: 'Shader',
-  texture: 'Texture',
-  animation: 'Animation',
-  container: 'Container',
-  list: 'List',
-  particles: 'Particles',
-};
-
 export async function overflow(t) {
   const { check, sleep, json, evaluate, shot, mutate, drag, clickText } = t;
 
@@ -105,14 +93,14 @@ export async function overflow(t) {
   const offered = await json('__gm.overlayTexts()');
   check(
     'the overflow button offers every tab that had to go',
-    narrow.hidden.every((tab) => offered.includes(LABELS[tab])),
+    narrow.hidden.every((tab) => offered.includes(TAB_LABELS[tab])),
     JSON.stringify({ offered, hidden: narrow.hidden }),
   );
-  await clickText(LABELS[wanted]);
+  await clickText(TAB_LABELS[wanted]);
   await sleep(400);
   const picked = await json('__gm.tabRow()');
   check(
-    `picking ${LABELS[wanted]} from the overflow menu opens it and puts it in the row`,
+    `picking ${TAB_LABELS[wanted]} from the overflow menu opens it and puts it in the row`,
     (await json('__gm.tab()')) === wanted && picked.shown.some((b) => b.tab === wanted),
     JSON.stringify({ tab: await json('__gm.tab()'), shown: picked.shown.map((b) => b.tab) }),
   );