Publish antd-linux-arm64 release artifact

[Nic-dorman]

Summary

Add antd-linux-arm64 to the release artifacts produced by .github/workflows/release.yml.

Background

The antd daemon is published on every tag as a set of platform-specific binaries. As of v0.7.0, the assets are:

• antd-linux-amd64
• antd-darwin-arm64
• antd-windows-amd64.exe
• SHA256SUMS

There is no Linux arm64 binary, which means consumers running antd on:

• AWS Graviton / Ampere / other ARM cloud instances
• Apple Silicon dev machines running Linux containers
• Raspberry Pi-class hardware

have to either cross-compile from source, run amd64 binaries under emulation (slow), or skip antd entirely on those hosts.

Scope

• Extend the release matrix in .github/workflows/release.yml to include aarch64-unknown-linux-gnu (or equivalent for the antd build system — likely cross on an Ubuntu runner, or a native linux-arm64 runner)
• Produce antd-linux-arm64 as a release artifact alongside the existing binaries
• Include it in SHA256SUMS

Acceptance

• The next tagged release lists antd-linux-arm64 in its assets
• gh release download <tag> --repo WithAutonomi/ant-sdk --pattern antd-linux-arm64 succeeds
• The binary runs on a real arm64 Linux host (basic smoke test: antd --version, antd --help)

Notes

This unblocks publishing multi-arch Docker images that bundle antd as a companion service — linux/arm64 images currently have to ship without a matching antd binary.