Fix #42: tip jar sheet abort in UIKit's focus engine (DEBUG/--uitest shim) + FR-1100-08 regression guard - #44

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/