PaneFooter items clip when NavigationView is collapsed

### Describe the bug

When the navigation pane is collapsed, the icons of `NavigationViewItem` elements placed inside `NavigationView.PaneFooter` get clipped. This issue is also observed in the WinUI 3 Gallery app.

### Steps to reproduce the bug

1. Open the WinUI 3 Gallery app and navigate to the **NavigationView** sample.
2. Scroll down to the **"API in action"** example.
3. Enable **"PaneFooter visible"**.
4. Collapse/close the navigation pane.

### Expected behavior

When the navigation pane is collapsed, the `PaneFooter` items should be fully visible without clipping, just like the other navigation items.

### Screenshots


### NuGet package version

WinUI 3 - Windows App SDK 1.6.5: 1.6.250205002

### Windows version

Windows 11 (24H2): Build 26100

### Additional context

_No response_

Start by reproducing the issue in the WinUI 3 Gallery NavigationView sample, using the “API in action” example and its PaneFooter visibility control. Inspect the NavigationView PaneFooter layout while the pane is collapsed; done means its items remain fully visible without clipping in the reproduced scenario.

Written by the indexing model from the issue text.