Measure engine coupling, QA harness use and contract coverage

Counters that may only fall, each with a committed baseline and a test
that fails on growth:

- report-engine-coupling.mjs gains layer modules that take the viewer
  in attachRenderer (33), layer folders with their own "view being
  restored" flag (9), engine.surface calls outside src/globe (41) and
  layer ids named in the engine switch (3).
- report-qa-harness.mjs counts QA scripts that launch Chrome themselves
  (98), wait with fixed sleeps (117), take the hidden loading screen as
  readiness (9), read Cesium-only objects (75) or define their own
  waitFor helpers (19).
- withCallLog records every contract member the contract suite calls on
  the fake engine; contractCoverage.test.mjs fails when a member outside
  contract-uncalled-baseline.json goes uncalled, and when a listed one
  is called now, so the list of 12 only shrinks.

scripts/qa-harness-baseline.json

@@ -0,0 +1,9 @@
+{
+  "metrics": {
+    "ownLaunch": 98,
+    "fixedSleeps": 117,
+    "loadingScreenReadiness": 9,
+    "cesiumOnlyReads": 75,
+    "ownWaitHelpers": 19
+  }
+}