Generate a meaningful Git commit message prompt

For the diff below, write a Conventional Commits-compliant subject (≤50 chars) and a short body (72-char line limit) only if needed.

Rules:
- Use imperative mood ("add" not "added").
- Prefer a single subject line; add a body only for the *why*.
- The type must be one of: feat, fix, refactor, perf, docs, test, chore, style.

Diff:
```diff
Git diff
```