🐛 Bug: cwd option doesn't work for in-memory Prettier

### Bug Report Checklist

- [x] I have tried restarting my IDE and the issue persists.
- [x] I have pulled the latest `main` branch of the repository.
- [x] I have [searched for related issues](https://github.com/JoshuaKGoldberg/formatly/issues?q=is%3Aissue) and found none that matched my issue.

### Expected

Formatting with Prettier when Prettier is installed formats from options.cwd

### Actual

Formatting with Prettier when Prettier is installed resolves from options.cwd, but formats from process.cwd().

### Additional Info

This isn't breaking anything for me, I just noticed it while taking a look at https://github.com/prettier/prettier/issues/17422#issuecomment-5287820840.

No file or test is named in the report. Start by locating the in-memory Prettier formatting path and trace how options.cwd is used for module resolution versus formatting. Confirm the fix by checking that formatting uses options.cwd rather than process.cwd().

Written by the indexing model from the issue text.