Fail the acceptance when a production build throws on a cold start of either engine

qa-strict-prod-smoke opens the keyless vite preview on each engine, switches once and fails on any page error. qa-strict-cold-chunks reports Cesium.js at a cold Navara start as a known gap instead of a failure.

scripts/qa-all-layer-switches.mjs

@@ -373,6 +373,7 @@ const runs = [
   ['strict-context-loss', 'strict-context-loss', []],
   ['strict-failure-matrix', 'strict-failure-matrix', [], [], 600],
   ['strict-cold-chunks', 'strict-cold-chunks', []],
+  ['strict-prod-smoke', 'strict-prod-smoke', []],
   ['strict-soak', 'strict-soak', [], soakRuns, 1200],
   [
     'strict-soak--long',