feat(plotnine): implement skewt-logp-atmospheric (#7565)

## Implementation: `skewt-logp-atmospheric` - python/plotnine

Implements the **python/plotnine** version of `skewt-logp-atmospheric`.

**File:**
`plots/skewt-logp-atmospheric/implementations/python/plotnine.py`

**Parent Issue:** #3802

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:robot: *[impl-generate
workflow](https://github.com/MarkusNeusinger/anyplot/actions/runs/26196391897)*

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Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Markus Neusinger <2921697+MarkusNeusinger@users.noreply.github.com>

Author: github-actions[bot]