The master PNG was fully opaque, so its white corners showed as a
square frame once macOS composited the icon onto its rounded plate.
Swap in the auditor-mode artwork, which has transparent corners.
Signed-off-by: Ludovic Vielle <ludovic@probo.com>
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>