fix(security): gate cached private-key operations on device unlock - #1

The process '/usr/local/lib/android/sdk/build-tools/34.0.0/apksigner' failed with exit code 2

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: r0adkll/sign-android-release@v1. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/