update to CN used with cert store

Author: JacobBarthelmeh

.github/workflows/windows-cert-store-test.yml

@@ -517,7 +517,16 @@ jobs:
           
           Write-Host "Client cert in store: $($importedCert.Subject)"
           Write-Host "Client cert thumbprint: $($importedCert.Thumbprint)"
-          Add-Content -Path $env:GITHUB_ENV -Value "CLIENT_CERT_SUBJECT=$($importedCert.Subject)"
+          # Extract CN from the subject for use as a cert store search string.
+          # The full X.500 DN contains commas which break command-line argument
+          # parsing, but CertFindCertificateInStore does substring matching so
+          # the CN alone is sufficient.
+          $cn = $importedCert.Subject
+          if ($cn -match 'CN=([^,]+)') {
+            $cn = $matches[1].Trim()
+          }
+          Write-Host "Client cert CN for store lookup: '$cn'"
+          Add-Content -Path $env:GITHUB_ENV -Value "CLIENT_CERT_SUBJECT=$cn"
         } else {
           # For file/x509: create a placeholder cert (not used, but keeps env var consistent)
           $clientCert = New-SelfSignedCertificate `