How can html, css, and js files be minified with gulp so that they can't be decompressed back?

Question

gulp.js

I use gulp-htmlmin, gulp-cssnano and gulp-jsmin for minification.
My task is this.
I am making two gulp builders:
1. gulp default
2. gulp build
The first builder I use when building my site, there is no need to minify it.
When I need to show the client an intermediate or final result, I run the second gulp and minify the html, css and js files.
The fact is that I found information on how to download the site from the browser completely with all the files and pictures.
That's why I don't want to work for free, it's a kind of insurance.
When the customer pays, I use the first gulp without minifications and give it to the customer, plus the rest of the sources.
So how do you compress files so you can't decompress them back?
Thanks in advance.