relay-compiler: Add Windows ARM64 (win-arm64) support

[BrunoRDS]

Summary

relay-compiler does not support Windows ARM64. Running it on a win32/arm64 system throws:

Error: Platform "win32 (arm64)" not supported.

This is because index.js only maps win32 + x64 to a binary, and falls through to null for arm64.

Suggested fix

Windows ARM64 has mature built-in x64 emulation, so the simplest fix is to fall back to the existing win-x64 binary:

} else if (process.platform === 'win32' && process.arch === 'arm64') { // ARM64 Windows can run x64 binaries via  emulation binary = path.join(__dirname, 'win-x64', 'relay.exe');
}

This is the same approach used for other tools that don't ship native ARM64 Windows binaries. The x64 binary runs  without issues under emulation.

Context

• Windows ARM64 devices (Surface Pro, Snapdragon Dev Kit, etc.) are increasingly common for development
• Linux ARM64 support was already added (resolving #3799) — this is the equivalent for Windows
• The fix is a 3-line change to  index.js  (and optionally  cli.js )