fix(windows): fix CI function name and purge return type handling

- Fix Test-IsProtectedPath -> Test-ProtectedPath in CI workflow
- Fix purge.ps1 to handle boolean return from Remove-SafeItem
- Add C:\Program Files and C:\Program Files (x86) to ProtectedPaths

.github/workflows/windows.yml

@@ -188,7 +188,7 @@ jobs:
           )
           
           foreach ($path in $protectedPaths) {
-              if (-not (Test-IsProtectedPath -Path $path)) {
+              if (-not (Test-ProtectedPath -Path $path)) {
                   Write-Host "✗ $path should be protected!" -ForegroundColor Red
                   exit 1
               }