Test layers on one engine and share selection and shader helpers

Layer display tests no longer re-check Cesium primitives in every layer:
they run on the fake engine, and one Cesium translation check per ground
kind lives in the Cesium engine's ground tests. Their harnesses are shared,
and the fake-engine, Cesium-engine and flights tests that repeated the
contract suite are gone, 340 tests in all.

The press-travel measurement is shared by the selection dispatcher and
CCTV, which loses its ScreenSpaceEventHandler shim and world-click module.
ALPR, installations and bikeshare share one selection keeper and selected
marker write. Layers with their own click rules keep their handlers.

Navara's pulse is a class like the ground pass, the ground and imagery
passes share the surface uniforms, and the colour, log-depth and occlusion
GLSL lives in one chunk module, each caller keeping its depth bias. The
ground suite runs inside the contract suite (--only=ground:), and fixture
and script names say what they test.

Behaviour is unchanged on both engines.

scripts/qa-cctv-v2.mjs

@@ -77,9 +77,9 @@
  */
 
 import puppeteer from 'puppeteer';
-import { watchW1Page, redact } from './qa-browserEvidence.mjs';
+import { watchBrowserPage, redact } from './qa-browserEvidence.mjs';
 import { blockPaidQaMaps } from './qa-map-policy.mjs';
-import { installCctvFixture } from './fixtures/w2/cctv.mjs';
+import { installCctvFixture } from './fixtures/layers/cctv.mjs';
 import fs from 'node:fs';
 import path from 'node:path';
 import { fileURLToPath } from 'node:url';
@@ -581,7 +581,7 @@ async function main() {
         if (terrainRequests.delete(request)) terrainActivityAt = Date.now();
       });
     await page.setViewport({ width: 1280, height: 800 });
-    watchW1Page(page, evidence, {
+    watchBrowserPage(page, evidence, {
       name: 'cctv-legacy',
       baseUrl: APP_URL,
       preview: getFlag('--preview'),