Update `Snap geometry edits` to include geometry guides

[duffh]

Description

Update Snap geometry edits sample to include geometry guides.

Type of change

• Other enhancement

Platforms tested on

• [x] WPF .NET 8
• [x] WPF Framework
• [x] WinUI
• [x] MAUI WinUI
• [x] MAUI Android
• [x] MAUI iOS
• [x] MAUI MacCatalyst

Checklist

• [x] Self-review of changes
• [x] All changes work as expected on all affected platforms
• [x] There are no warnings related to changes
• [x] Code is commented and follows .NET conventions and standards
• [x] Codemaid and XAML styler extensions have been run on every changed file
• [x] No unrelated changes have been made to any other code or project files
• [x] Screenshots are correct size and display in description tab (800 x 600 on Windows, MAUI mobile platforms use the MAUI Windows screenshot)