Offer nested_frame.to_pyarrow_array(s) method

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**Feature request**

See

https://github.com/light-curve/light-curve-python?tab=readme-ov-file#nested-pandas

```
import light_curve as lc
import nested_pandas as npd
# removes import pyarrow as pa
...
result = feature.many(ndf["lightcurve"].to_pyarrow_arrays()), n_jobs=-1)
```

**Before submitting**
Please check the following:

- [ ] I have described the purpose of the suggested change, specifying what I need the enhancement to accomplish, i.e. what problem it solves.
- [ ] I have included any relevant links, screenshots, environment information, and data relevant to implementing the requested feature, as well as pseudocode for how I want to access the new functionality.
- [ ] If I have ideas for how the new feature could be implemented, I have provided explanations and/or pseudocode and/or task lists for the steps.

Start with the linked Nested Pandas example and locate the nested_frame API entry point for the requested to_pyarrow_array(s) method. Confirm the expected return shape from the feature.many usage shown in the issue; done means callers can use the nested frame column directly without importing pyarrow.

Written by the indexing model from the issue text.