Add branded Finder icon for Probo Agent.app

The macOS URL-handler bundle had no CFBundleIconFile, so
Finder showed the generic app icon after PKG install. Keep a
single master PNG and generate AppIcon.icns at build time
with sips/iconutil, matching the auditor-mode approach.

Signed-off-by: Ludovic Vielle <ludovic@probo.com>

pkg/dnsverify/names.go

@@ -51,6 +51,7 @@ func EqualNames(a, b string) bool {
 // itself, not its apex.
 func CheckNames(hostname string) ([]string, error) {
 	hostname = strings.ToLower(strings.TrimSpace(hostname))
+
 	hostname = strings.TrimSuffix(hostname, ".")
 	if hostname == "" {
 		return nil, fmt.Errorf("cannot build DNS check names: empty hostname")