Inverted y-axis Area chart

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## What did you do?

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## What did you expect to happen?

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I want to complete a chart like this, where the upper y-axis on the left is 0 and the lower is 100. I tried to set leftAxis.inverted to true.
But I got the picture below. What I want is that after the y-axis is reversed, the lower part is still colored.
How should I set it up
## What happened instead?

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## Charts Environment

**Charts version/Branch/Commit Number:**
**Xcode version:**
**Swift version:**
**Platform(s) running Charts:**
**macOS version running Xcode:**

## Demo Project

ℹ Please link to or upload a project we can download that reproduces the issue.

Start by reproducing the Area chart shown in the issue with leftAxis.inverted set to true, using the attached images as the expected and actual behavior. Trace how axis inversion affects the area fill, then verify that the lower portion remains colored after inversion; the issue provides no file, test, version, or demo-project entry point.

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