Build: landing/learn shed eager Monaco+Vega; post-build gate + immutable asset caching

package.json

@@ -6,7 +6,7 @@
   "description": "A browser-based snippet manager for Vega-Lite visualizations.",
   "scripts": {
     "dev": "vite",
-    "build": "tsc --noEmit && vite build",
+    "build": "tsc --noEmit && vite build && node scripts/check-light-entries.mjs",
     "preview": "vite preview",
     "typecheck": "tsc --noEmit",
     "test": "vitest run",
@@ -56,6 +56,7 @@
     "@types/react": "^19.2.16",
     "@types/react-dom": "^19.2.3",
     "@vitejs/plugin-react": "^5.2.0",
+    "ajv": "^8.20.0",
     "eslint": "^10.4.1",
     "eslint-plugin-react-hooks": "^7.1.1",
     "eslint-plugin-react-refresh": "^0.5.2",