A test that waits for a deadline somebody guessed is waiting for the wrong thing, so it waits for the editor (#93)

The suite spent 88% of its step time asleep: 564 s of steps, 496 s of
them in sleep(n) - fixed spans estimated by hand and then copied from
step to step. That is why it was slow, and why it flickered.

The signal is afterFrames(count, timeout) in ui/render.ts, exposed as
__gm.afterFrames(). It wakes the loop itself, because an editor that
draws nothing would never redeem a promise of a frame, and it gives up
after a timeout instead of hanging the run. settle() in the harness
waits two drawn frames (~32 ms) instead of 150-300 ms and falls back to
sleep(150) when the hook is missing (an old build): silently not
waiting would make every later check a coin toss.

Every action goes through it now - click, doubleClick, wheel, drag,
dragAsset, press, typeText, select, mutate, undo, redo - and with that
about 550 sleep() calls behind those actions became redundant, helpers
that are nothing but a mutate in a coat included. What a frame cannot
answer got its own condition instead: waitUntil(expr), play()/stop()
waiting on __gm.state.mode rather than on 300 ms, saved() for the
autosave (the two hand-written polling loops sampled at 300 ms for
something that arrives after a second), and showTab() as a real tool -
47 places called evaluate("__gm.showTab(...)") raw, and 24 of them
waited for nothing at all and read the old panel.

564 s -> 243 s of step time, the waiting share 88% -> 76%. Three kinds
of wait were kept, and each one bit when it was taken away: loading
bytes (textures, fonts), game time that a repaint cannot stand in for
(time scale, shader and particle clocks, the live values a running
graph carries), and the inertia the scroll step measures on purpose.

Two things the new speed uncovered, both real: 25-animation read the
frame menu unfiltered and had frozen an incomplete list (the CI failure
on c990dbc), and 33-render-on-change measured idleness while the
autosave of the step before was still painting - it waits for
saveStatus to leave dirty/saving now, so it measures that nothing
happens any more instead of that it waited long enough.

tools/e2e/lib/scaffold.mjs

@@ -76,7 +76,6 @@ export async function scaffoldBehavior(t, options) {
       make(${JSON.stringify(logicId)}, ${JSON.stringify(assetId)}, ${JSON.stringify(boxId)}, 0, ${JSON.stringify(name)}),
     );
   `);
-  await t.sleep(400);
 
   return {
     assetId,
@@ -93,7 +92,6 @@ export async function scaffoldBehavior(t, options) {
         scene.objects = scene.objects.filter((o) => !objects.includes(o.id));
         p.assets = p.assets.filter((a) => !assets.includes(a.id));
       `);
-      await t.sleep(300);
       return t.json(`{
         objects: __gm.sceneObjects().filter((o) => ${JSON.stringify([boxId, logicId])}.includes(o.id)).length,
         assets: __gm.state.project.assets.filter((a) => a.id === ${JSON.stringify(assetId)}).length,
@@ -125,10 +123,8 @@ export async function openTab(t, tab) {
   const row = await t.json('__gm.tabRow()');
   if (row.hidden.includes(tab)) {
     await t.clickText('»');
-    await t.sleep(300);
   }
   await t.clickText(TAB_LABELS[tab]);
-  await t.sleep(400);
 }
 
 /**
@@ -144,11 +140,9 @@ export async function pickAssetType(t, label) {
   let scrolled = false;
   if (box && (!p || p.y > box.y + box.h - 4)) {
     await t.wheel(box.x + box.w / 2, box.y + box.h / 2, 300);
-    await t.sleep(250);
     p = await t.locate(label, true);
     scrolled = true;
   }
   await t.click(p.x, p.y);
-  await t.sleep(250);
   return { box, p, scrolled };
 }