refactor: replaced manual byte formatting with format_bytes utility

[law65horizon]

Closes #34

Replaced all manual byte formatting across the codebase with the existing format_bytes utility from src/utils/formatting.rs, as directed by the maintainer.

Files changed:

• src/main.rs
• src/ui/commands.rs
• src/ui/tui.rs
• src/ui/render.rs — also removed the now-redundant format_size function
• src/core/scan.rs
• src/core/delta.rs
• src/utils/mod.rs — added to expose the utils module

[SickleFire]

Hi @law65horizon ,

Thank you for taking the time to update the codebase to use the new format_bytes implementation. This is a great cleanup effort and ensures consistency across the entire repository.

The changes look solid. Merging rn.