How to organize applications ?

Hello to all,

I'm creating a small personal cms with CI4, but I'm stuck on the organization of the template system.

My architecture, based on modules is the following:
- app
- public
-- assets
--- default-theme
---- style.css
---- js.css
- companyname
-- Admin
-- Blog
-- Catalog
-- Themes
--- default-theme
---- blog
----- template.php
----- post.php

So I have a "Themes" folder which will contain the different templates.

I would also like to know the best way to manage the CSS & JS files of the template (assets/default-theme) in the same folder as the Php files of the module (tcms/Themes/default-theme).

Thank you in advance for your help and happy holidays.