Expand Pester coverage across install, tweaks, and UI workflows (#4792)

* Harden Pester CI and discard runspace return values

* Add prioritized test backlog

* Add WinUtil action logging

* Add config integrity tests

* Add XAML control wiring tests

* Add registry and service helper tests

* Add package manager tests

* Add runspace behavior tests

* Add tweak orchestration tests

* Add install workflow tests

* Add update profile tests

* Add AppX removal tests

* Log package installer output

* Add UI state helper tests

* Pin Pester test runner version

* Expand Win11 Creator tests

* Add preferences and theme tests

* Add search filter tests

* Add compile contract tests

* Use single WinUtil session log

* Remove installer output logging helper

* Handle locked WinUtil transcript log

* Avoid appending to active transcript log

* Log install uninstall package identities

functions/private/Show-WinUtilMessage.ps1

@@ -0,0 +1,14 @@
+function Show-WinUtilMessage {
+    <#
+    .SYNOPSIS
+        Shows a WinUtil message box and returns the selected result.
+    #>
+    param (
+        [string]$Message,
+        [string]$Title = "Winutil",
+        $Button = "OK",
+        $Icon = "Information"
+    )
+
+    [System.Windows.MessageBox]::Show($Message, $Title, $Button, $Icon)
+}