refactor: improve formatting of success message

The success message in the core_messages.sh file has been updated to include square brackets around "OK" for better visibility.

lgsm/modules/core_messages.sh

@@ -413,7 +413,7 @@ fn_print_ok_eol() {
 }
 
 fn_print_ok_eol_nl() {
-	echo -e "${green}OK${default}"
+	echo -e "${green}[ OK ]${default}"
 	fn_sleep_time
 }