fix: restore skin controls and desktop portrait compatibility

Respect host root layout, draw the scrim once, discover appearance controls without build hashes, and recover failed portraits independently. Add unit and real-browser regression coverage.

Refs #8, #12, #15, #10, #13. Native Desktop acceptance remains pending; no release.

package.json

@@ -48,7 +48,8 @@
   ],
   "scripts": {
     "build": "node ./scripts/build-client.mjs",
-    "test": "vitest run"
+    "test": "vitest run",
+    "test:compatibility": "npm run build && node ./scripts/test-client-compatibility.mjs && node ./scripts/test-client-runtime.mjs"
   },
   "dsh": {
     "bundle": {
@@ -70,6 +71,7 @@
   "devDependencies": {
     "@types/react": "~18.3.1",
     "esbuild": "^0.25.0",
+    "playwright-core": "^1.64.1",
     "vitest": "^4.1.10"
   }
 }