[Windows] TabBarDisabledColor is not applied when the TabBar is in a disabled state

### Description

When a Tab is disabled (IsEnabled = false), the TabBarDisabledColor property is expected to change the icon and text color of the disabled Tab.
This works correctly on Android , but on windows the TabBarDisabledColor is not applied, and the TabBar continues to use the default system disabled color.

### Steps to Reproduce

1. https://github.com/dotnet/maui/blob/inflight/candidate/src/Controls/tests/TestCases.HostApp/Issues/Issue32995.cs
2. https://github.com/dotnet/maui/tree/main/src/Controls/tests/TestCases.HostApp/FeatureMatrix/Shell/ShellTabbed
3. Set TabBarDisabledColor="Green" in the Shell.
4. Disable one of the tabs.
5. Run the sample on Windows.
6. Observe that the disabled Tab does not use the green color and instead shows the default disabled color.

### Link to public reproduction project repository

_No response_

### Version with bug

10.0.50

### Is this a regression from previous behavior?

Not sure, did not test other versions

### Last version that worked well

_No response_

### Affected platforms

Windows

### Affected platform versions

_No response_

### Did you find any workaround?

_No response_

### Relevant log output

```shell

```

Start with src/Controls/tests/TestCases.HostApp/Issues/Issue32995.cs and the ShellTabbed feature-matrix sample, then run the reproduction on Windows. Set TabBarDisabledColor to Green and disable a tab; done means its icon and text use the configured green color instead of the default system disabled color.

Written by the indexing model from the issue text.