Support installation for arm64 architecture

[jdragonbae]

This patch supports installation for arm64 architecture.
Since go-ios supports arm64 in #399,
we can use arm64 instead of amd64 for installation.

[danielpaulus]

Thanks!

[jdragonbae]

@danielpaulus Thanks for the review.
Can we merge this PR into main?

[danielpaulus]

@jdragonbae I had to revert #399 because it broke the release pipeline. I will try and double check this week that the change above works with the reverted state too.

[danielpaulus]

Thank you for this, @jdragonbae — and apologies it sat so long. 🙏 You were absolutely right that Apple Silicon shouldn't be stuck on an amd64/Rosetta binary, and this PR pointed at the real gap.

Closing it now because the underlying issue has since been solved a different way and the change is effectively a no-op against current main:

• ARCH_MAPPING already includes "arm64": "arm64" on main.
• The release workflow now builds a universal (lipo) macOS binary and ships that same binary to both the darwin-amd64 and darwin-arm64 dist folders (release.yml: lipo ... -create -output bin/ios, then cp ./mac-bin/ios into both). So even the legacy "using amd64 build on M1 mac" fallback path now installs a binary that runs natively on Apple Silicon — no Rosetta.

The only remnant is that the "using amd64 build on M1 mac" log line is now misleading (it's a universal binary, not amd64), which we'll tidy up separately.

So the practical outcome you wanted — native arm64 installs on Apple Silicon — already ships. Thanks again for flagging it and for your patience! 🎉