refactor codebase

Hi @puikinsh , I have a suggestion for you, especially regarding this repository. I think it would be better if the code in this repo contained the source files instead of only the rendered output. This could make it easier for others to help maintain the repository. For example, when we want to change the menu, we currently have to edit all the HTML files in the repo. Doesn’t that add unnecessary extra work? Why not structure it like your other repo ([Adminator](https://github.com/puikinsh/Adminator-admin-dashboard)), where we only need to update one file and the rendered result automatically applies to all pages? Maybe you already have a codebase like this internally, but perhaps it’s private. Also, for the JavaScript, it might be better to separate the scripts that handle the core template functionality from the dummy/sample data used for specific pages (such as chart data, etc.). Thank you for responding to my issue.