Pin to windows-2022 runners

[Arlodotexe]

Background

On September 30, 2024, GitHub changed the windows-latest runner label to point to windows-2025 (previously windows-2022). The Windows Server 2025 runners removed all preinstalled Windows SDKs except the latest version.

This change immediately broke all CI builds across the Windows Community Toolkit repositories. Our builds require two specific Windows SDK versions:

• SDK 17763 for UWP (TargetFramework)
• SDK 19041 for WinAppSDK (TargetFramework)

Upgrading these TFM versions would force all consumers to update, so we maintain these specific SDK requirements to preserve backward compatibility.

Problem

Current Impact:

• All CI builds failing with SDK-related errors
• Cannot build or test any toolkit components
• Blocks all development, testing, and release workflows
• Affects both CommunityToolkit/Labs-Windows and CommunityToolkit/Windows repositories

Root Cause:

• windows-latest now resolves to windows-2025
• Windows 2025 runners only include the latest Windows SDK
• Our builds require SDK 17763 (UWP) and SDK 19041 (WinAppSDK)
• These specific SDK versions are no longer present on windows-2025 runners
• Cannot upgrade TFMs without forcing all consumers to update

Tracked in: CommunityToolkit/Labs-Windows#741

Solution

Pin all Windows runner specifications to windows-2022 to restore SDK availability:

Changes:

• windows-latest → windows-2022 (3 jobs affected)
  • Xaml-Style-Check job
  • project-template job
  • new-experiment job

Strategy:

1. Test with windows-2022 to verify if previous D drive disk space issues are resolved
2. If successful, this provides immediate CI restoration
3. If windows-2022 still has disk space issues, parent repos use windows-2022-large (which exists to resolve out of disk space errors from missing D drive)

Jobs Updated:

1. Xaml-Style-Check - Lightweight XAML styling validation
2. project-template - Template building and validation
3. new-experiment - Experiment generation and testing

Testing:

• CI will run on this PR to validate runner compatibility
• Build success confirms SDK availability on windows-2022
• If builds fail with disk space errors, we'll need to escalate runner size