The previous text match on signtool output was flaky: signtool interleaves
stdout (chain details) and stderr (error), so the wrapped "untrusted root"
phrase stayed contiguous for one file but was split for another, causing the
verify step to pass orca-slicer.exe but throw on OrcaSlicer.dll.
Use Get-AuthenticodeSignature instead, whose StatusMessage is a single clean
string, to decide the untrusted-root exception. signtool remains the strict
primary check; this only governs the -AllowUntrustedRoot test-cert path.