Consider adopting @pierre/diffs for diff rendering (split view + theming)

[1Jack2]

Hi! I’d like to propose evaluating @pierre/diffs (docs) as the web diff renderer.

Motivation

• GitHuman’s core value is visual review. A built-in split (side‑by‑side) diff could improve readability for large
  changes.
• The library appears to support unified + split layouts and themeable styling, which might reduce custom diff UI
  maintenance.

Potential benefits

• Split view support out of the box.
• Theming support (light/dark) might align with future theme toggle.
• Built‑in annotations could map to our comment system.

Related issue
#7
#8

[AlphaTechini]

Don't worry we don't need an external library my latest PR has those changes #12