Run the layer acceptance under a default-deny network policy with per-layer assertion manifests and strict switch contracts

Every scenario runs through scripts/qa-strict-harness.mjs: each page, frame and worker gets an ordered block list before it runs (paid hosts and routes first, then only the preview, declared fixtures, keyless probes and cached free tile hosts), switches with real input on the picker, and records its assertions per layer and engine. The runner reads the catalog from the live page, fails any layer without an assertion on either engine, can build and serve a keyless checkout itself, and adds rapid, hidden-tab, context-loss, failure-injection, cold-chunk and soak scenarios. The main chunk gets a 1% size budget.

scripts/main-chunk-baseline.json

@@ -0,0 +1,6 @@
+{
+  "gzipBytes": 1920969,
+  "allowanceBytes": 19210,
+  "measuredAt": "a5d78b00, keyless build (GOOGLE_MAPS_API_KEY and CESIUM_ION_TOKEN empty), entry index-CV-avk6m.js, 5 933 796 bytes, gzip level 9",
+  "allowance": "1% of the baseline; growth past it fails npm run check:main-chunk until the baseline is raised on purpose"
+}