Give QA scripts one launch, readiness and geometry helper

scripts/qa/browser.mjs launches headless Chrome with QA_ANGLE and the
shared Chrome lookup; scripts/qa/ready.mjs adds frame, tile and transition
readiness and bounded polling; scripts/qa/geometry.mjs hands page
evaluations the engine-neutral geometry without dev-only source URLs.
CODE-BOUNDARIES gains the rule for new QA scripts.

scripts/qa/geometry.test.mjs

@@ -0,0 +1,24 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import vm from 'node:vm';
+import { evaluateWithGeo } from './geometry.mjs';
+
+test('page geometry works without source routes or native engine constructors', async () => {
+  const page = {
+    evaluate: (callback, ...args) =>
+      vm.runInNewContext(`(${callback})(...${JSON.stringify(args)})`),
+  };
+  const result = await evaluateWithGeo(
+    page,
+    (geo, lon, lat, height) => {
+      const point = geo.cartesian3.fromDegrees(lon, lat, height);
+      return geo.cartographic.fromCartesian(point);
+    },
+    23,
+    -12,
+    650,
+  );
+  assert.ok(Math.abs(result.longitude - (23 * Math.PI) / 180) < 1e-12);
+  assert.ok(Math.abs(result.latitude + (12 * Math.PI) / 180) < 1e-12);
+  assert.ok(Math.abs(result.height - 650) < 1e-6);
+});