ci: modernize GitHub Actions workflow to fix Windows builds

[matthewjablack]

Problem

The Windows CI builds were being cancelled immediately due to deprecated runners and outdated GitHub Actions.

Solution

This PR modernizes the GitHub Actions workflow to fix the immediate cancellation issues:

Changes Made

• Windows Runner: Updated from windows-2019 (deprecated) to windows-latest
• Visual Studio Generator: Updated from 'Visual Studio 16 2019' to 'Visual Studio 17 2022'
• GitHub Actions: Upgraded all actions/checkout from v2 to v4
• Mac Runner: Changed from self-hosted to macos-latest (Apple Silicon ARM64)

Why These Changes

• windows-2019 is being phased out by GitHub and causes job cancellations
• actions/checkout@v2 is deprecated and can cause security warnings/failures
• VS 2019 may not be available on newer Windows runners
• ARM64 macOS testing provides better coverage for Apple Silicon builds

Testing

• Windows builds should now start successfully instead of being cancelled
• All runners use modern, supported versions
• ARM64 macOS builds will test Apple Silicon compatibility
• No functional changes to build process, only infrastructure updates

Fixes the immediate Windows build cancellation issues reported in the CI.