UninstallAppTool
pm uninstall [-k] <pkg> — silently uninstall an app by package name, no user prompt. Success is detected by "Success" in stdout.
Privilege: requires a working ShellBackend.
Params: package_name (required), keep_data (optional, default false → adds -k to retain the app's data/cache directories).
On success the result map carries success (true) and package_name.