In self-hosted, where should I put the ".scss" file for the theme?

Thank you very much for your answer and advice.
Indeed I installed “taiga-front-dist”.
I didn’t think there was any other way.

I looked for documentation on how to compile “taiga-front” and found “Taiga: Setup development environment”.

Unfortunately, I’m not an expert in web programming. (I even found out about gulp for the first time)
So, I would appreciate it if you could answer two additional questions.

(1) To compile “taiga-front”, should I follow this “Setup development environment”? (“4.3 Final steps” ends with running “npm start”)

(2) Should I reconfigure not only “taiga-front” but also “taiga-back” and “taiga-events” according to the “Setup development environment” and operate with these three modules?
The production environment on my server consists of five modules: “taiga-back”, “taiga-async-tasks”, “taiga-front-dist”, “taiga-events”, and “taiga-protected”.
I’m concerned that the dependencies and collaboration methods may be different between my production environment and the development environment I’m about to create.
Of course, if there are no particular problems, I’d like to just compile “taiga-front”.

Thank you for your help.