Fix GUI operation script scope

src/MsPrivate.Execution.psm1

@@ -2,6 +2,19 @@ Set-StrictMode -Version Latest
 $ErrorActionPreference='Stop'
 Import-Module (Join-Path $PSScriptRoot 'MsPrivate.IO.psm1') -ErrorAction Stop
 
+function New-MsPrivateScriptInvoker {
+    param([Parameter(Mandatory)][string]$Root)
+    $runtimeRoot=[IO.Path]::GetFullPath($Root).TrimEnd([IO.Path]::DirectorySeparatorChar)+[IO.Path]::DirectorySeparatorChar
+    if(-not[IO.Directory]::Exists($runtimeRoot)){throw "Runtime root does not exist: $runtimeRoot"}
+    {
+        param([Parameter(Mandatory)][string]$Script,[hashtable]$Parameters=@{})
+        if($Script-notmatch'^[A-Za-z0-9][A-Za-z0-9.-]*\.ps1$'){throw "Invalid runtime script name: $Script"}
+        $path=[IO.Path]::GetFullPath((Join-Path $runtimeRoot $Script))
+        if(-not$path.StartsWith($runtimeRoot,[StringComparison]::OrdinalIgnoreCase)-or-not[IO.File]::Exists($path)){throw "Runtime script was not found: $Script"}
+        & $path @Parameters|Out-Host
+    }.GetNewClosure()
+}
+
 function Invoke-MsPrivateGroupPlan {
     param(
         [Parameter(Mandatory)][object[]]$Groups,
@@ -36,4 +49,4 @@ function Invoke-MsPrivateGroupPlan {
     $report
 }
 
-Export-ModuleMember -Function Invoke-MsPrivateGroupPlan
+Export-ModuleMember -Function Invoke-MsPrivateGroupPlan,New-MsPrivateScriptInvoker