Port GazeInteractionLibrary from 7.x

**Source**: Microsoft.Toolkit.Uwp.Input.GazeInteraction (7.x)
**Destination**: CommunityToolkit.WinUI.* (8.x) — TBD

## Prerequisites

- [ ] Labs-GazeControls relationship needs evaluation

## Porting Basics

- [ ] Namespace updated to `CommunityToolkit.WinUI.*`
- [ ] Code for UWP, WinUI3 and Uno Platform consolidated
- [ ] Desired MultiTargets configured
- [ ] Sample code migrated
- [ ] Concept docs migrated
- [ ] Tests migrated and passing

## Quality Evaluation

See [Porting Criteria](https://github.com/CommunityToolkit/Windows/wiki/Component-Quality-Evaluation) for detailed evaluation guidance.

- [ ] UX: Accessibility reviewed
- [ ] UX: Visual design reviewed
- [ ] UX: Interaction patterns appropriate
- [ ] DX: API surface reviewed
- [ ] DX: API flexibility appropriate
- [ ] DX: Documentation updated
- [ ] MX: Breaking changes documented
- [ ] MX: Domain isolation appropriate
- [ ] MX: Test coverage adequate

## Tracking Gaps

*Sub-issues appear in the task list when linked.*

## Closing

- [ ] All Porting Basics complete
- [ ] Quality Evaluation reviewed
- [ ] Gaps filed as sub-issues

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## 7x Documentation Inventory

**Docs ported to 8x**: n/a

**Docs not in 8x**:
- Summary
- Prerequisites
- Supported Features
- Gaze Concepts
- PointerState Properties
- GazeInput Properties
- GazeElement Events
- StateChangedEventArgs Properties
- DwellProgressEventArgs Properties
- DwellInvokedRoutedEventArgs Properties
- Examples
- To enable gaze interactions on the entire XAML page
- To enable gaze interactions on a portion of the page
- To change the dwell time for a control
- Animations

## 7x Source Inventory

**Source ported to 8x**: n/a

**Source not ported to 8x**:
- [Microsoft.Toolkit.Uwp.Input.GazeInteraction](https://github.com/CommunityToolkit/WindowsCommunityToolkit/tree/c8f76d072df53d3622fb5440d63afb06cb9e7a10/Microsoft.Toolkit.Uwp.Input.GazeInteraction)
- Related: [CommunityToolkit.Labs.Uwp.GazeControls](https://github.com/CommunityToolkit/Labs-GazeControls/tree/main/CommunityToolkit.Labs.Uwp.GazeControls)

## Notes

- Not currently planned for porting. Open to community interest.
- **Related work**: Labs-GazeControls may provide migration path.
- **Archive redirect**: https://learn.microsoft.com/en-us/dotnet/communitytoolkit/windows/archive/gaze