Update Node.js LTS to v20.19.0

Node.js v20 entered Maintenance LTS six months ago. Update the version
from 20.11.0 (released over a year ago) to 20.19.0, the latest LTS
release from last month.

This ensures the project leverages recent Node.js improvements,
including security updates, and stays on a supported LTS track.

core/vendor/package.json

@@ -13,6 +13,6 @@
   },
   "engine-strict": true,
   "engines": {
-    "node": ">=20.11.0"
+    "node": ">=20.19.0"
   }
 }