Restore the conditions eight converted QA scripts were waiting for

The harness conversion replaced pauses that stood in for real conditions
with camera readiness: the cables and infrastructure idle checks started
measuring while the overlay was still fading in after moveEnd, directions
sampled before its maneuver dots had ground cells, three scripts clicked
before the loading cover was gone, the credits check hit-tested during UI
transitions, and the oblique traffic flight lost its height cap. Each now
waits for its condition; idle checks observe without requesting frames
and record the reasons of the frames they count; readiness waits for the
startup cover and no longer requests frames while polling.

scripts/qa-cables-overlay.mjs

@@ -2,6 +2,7 @@
 // Cesium-only probes: native DataSource counts and scene-render timing measure the Cesium cable adapter.
 import { evaluateWithGeo } from './qa/geometry.mjs';
 import { whenSettled } from './qa/ready.mjs';
+import { measureIdleRender } from './qa/idle.mjs';
 import { launchBrowser, closeBrowser } from './qa/browser.mjs';
 /**
  * qa-cables-overlay — submarine-cable label path measurement + contract gate.
@@ -184,12 +185,8 @@ try {
     : 'scene.render cost, cables ON, 10s orbit', frameCost);
 
   // ── d. parked idle honesty (labels must not force continuous render) ──
-  await whenSettled(page); // orbit stop + fades settle
-  const idle = await page.evaluate(() => new Promise((resolve) => {
-    let renders = 0;
-    const remove = window.__godsEyeView.engine.frames.postRender.addEventListener(() => { renders += 1; });
-    setTimeout(() => { remove(); resolve({ renders }); }, 5_000);
-  }));
+  await whenSettled(page);
+  const idle = await measureIdleRender(page);
   report(control
     ? 'parked idle, control (postRender fires / 5s)'
     : 'parked idle with cables ON (postRender fires / 5s)', idle);