Migrate and stabilize PowerToys UI tests from WinAppDriver/Selenium to Microsoft.PowerToys.UITest.Next and winappcli. Use for ports, new UITest projects, flaky CI tests, persistent local-VM validation on Hyper-V, resettable clean-baseline runs, Settings IPC authentication/test signing, Explorer/Shell selection, preview handlers, thumbnail providers, hotkey activation, stateful process lifecycle, composed WinUI/WebView visual baselines, or cross-window/foreground failures. Covers APIs, scaffolding, test design, diagnostics, agentic execution, and CI hardening. Keywords: UI test, UITests, UITest