Summary

This PR enables vcpkg binary caching using GitHub Actions cache (x-gha) to significantly improve CI/CD pipeline performance and reduce build times across all platforms.

Changes

• Binary caching configuration: Added VCPKG_BINARY_SOURCES environment variable to use GitHub Actions cache
• Stronger cache keys: Enhanced cache key generation with vcpkg commit hash, triplet, and configuration files
• Standardized triplets: Explicitly set VCPKG_DEFAULT_TRIPLET for consistent builds across platforms
• Conditional installation: Skip vcpkg install step when cache is already available
• Documentation update: Updated workflow improvements documentation with current status

Benefits

• ⚡ Faster CI builds: Reuse previously built packages instead of rebuilding from source
• 💾 Reduced bandwidth: Minimize vcpkg package downloads
• 🔄 Better cache invalidation: More precise cache keys ensure proper cache updates
• 🎯 Consistent builds: Explicit triplet configuration prevents platform-specific issues

Platform Coverage

• ✅ Ubuntu (Clang)
• ✅ Ubuntu (GCC)
• ✅ Windows (MinGW)
• ✅ Windows (MSYS2)
• ✅ Windows (Visual Studio)

Testing

All CI workflows have been tested and are passing with the new binary caching configuration.

Notes

The x-gha binary source is GitHub's recommended approach for vcpkg binary caching in Actions, providing automatic cache management without additional setup.