calaos_installer: fix darwin install (#46629)

On darwin this builds an application instead of a binary.

/cc ZHF #45961

pkgs/misc/calaos/installer/default.nix

@@ -16,7 +16,10 @@ stdenv.mkDerivation rec {
 
   qmakeFlags = [ "REVISION=${version}" ];
 
-  installPhase = ''
+  installPhase = if stdenv.isDarwin then ''
+    mkdir -p $out/Applications
+    cp -a calaos_installer.app $out/Applications
+  '' else ''
     mkdir -p $out/bin
     cp -a calaos_installer $out/bin
   '';