feat(language): support for Nushell language

### Problem Statement

I would like to add support for Nushell to ocr.

### Proposed Solution

Nushell reviews available for users trying to review .nu files.

### Alternatives Considered

_No response_

### Affected Area

Documentation

### Additional Context

This issue is currently **claimed** by @wu21-web
Nushell: https://github.com/nushell/nushell

The issue identifies Nushell and .nu files but names no files, tests, or entry points. Start by reviewing how existing language support is organized and the linked Nushell project; done should mean reviews can process Nushell files as described, with the documentation updated accordingly.

Written by the indexing model from the issue text.