feat: general fixes & style enh

[PietroTambu]

Description

Hi, I want to share with you minor changes I make for my filebrowser.

1. Style changes: increased border-radius for buttons, input and modal.
2. Typo fix: colunms -> columns.
3. Added a Makefile target for FrontEnd development + default goal := help.
4. Switch ./scripts/* to node package execute (npx).

Let me know what you think of these changes or if you see any critical issues. 😄

here is a short video:

filebrowser.mov

Thank you!
Pietro.