Show changelog links in `vp up -i` output instead of package URLs

### Summary

Direct user feedback suggests `vp up -i` would be more useful if it linked to changelog information rather than the generic package URL.

Reference: https://bsky.app/profile/nestor.rip/post/3mssje4iqu22g

### Requested change

- For `vp up -i`, show an npmx link to the package changelog instead of the package URL

### Why this matters

When reviewing updates interactively, changelog context is often more actionable than a homepage or package URL.