fix(jni): preserve Unicode across string and exception boundaries - #1098

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-java@f4f1212c880fdec8162ea9a6493f4495191887b4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/