Add FxNode render graph playground

Add persistent render graph loadouts, grouped node authoring, code-appending apply behavior, explicit playground lighting, and resilient worker startup.

Amp-Thread-ID: https://ampcode.com/threads/T-01a033d4-0e44-708e-af0e-6166283416ff
Co-authored-by: Heaust Azure <heaust.azure@gmail.com>

package.json

@@ -12,8 +12,9 @@
     "server": "go run ./server",
     "coredocs": "vitepress dev coredocs --host 0.0.0.0 --port ${PORT:-8080}",
     "build:coredocs": "vitepress build coredocs",
-    "test": "npm run test:handles",
+    "test": "npm run test:handles && npm run test:fxnode-rg",
     "test:handles": "npm test --workspace @yawn/handles",
+    "test:fxnode-rg": "npm test --workspace @yawn/fxnode-rg",
     "test:handles:screenshots": "npm run test:screenshots --workspace @yawn/handles"
   },
   "devDependencies": {