Organize CSS/JS files into one or more files

I have a WordPress website with custom code spread across multiple locations (Customizer, plugins, child theme, etc.). I need a developer to reorganize everything into a clean, maintainable structure — either a single consolidated file or multiple files grouped by category (product page, cart, checkout, shop page, etc.). No new features are required. The goal is clean organization, removal of duplicates, and keeping all existing functionality intact. Please make fixed price offer, or estimate for hourly.