Fix release pipeline (macOS runner + Node.js 24)

Add GitHub Actions release workflow for multi-platform binaries

Builds darwin/amd64, darwin/arm64, windows/amd64, and windows/arm64
binaries on tag push. Uses llvm-mingw for Windows arm64 CGO support.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>