Release pipeline: add aarch64 parity

[danbugs]

The PR validation workflow builds and tests on aarch64, but the release pipeline (CreateRelease.yml) is still x86_64-only. Items to address:

• Guest builds: build-guests passes arch: X64 only — add an arm64 build and upload artifacts with arch-qualified names
• Benchmarks: dep_benchmarks.yml hardcodes X64 in its runs-on label and the benchmark matrix in CreateRelease.yml only covers {hyperv-ws2025, mshv3, kvm} x {amd, intel} — add aarch64/apple combos (requires runner pool availability)
• C API artifacts: tar-headers and tar-static-lib in the Justfile hardcode x86_64-hyperlight-none paths — add aarch64 equivalents and upload them in the release step
• Host build verification: build-rust-ubuntu runs on X64 self-hosted runners only — add an aarch64 build job
• Release upload step: the gh release create commands list only x86_64 benchmark and C API tarballs — add the new aarch64 artifacts

Some of these may be blocked on aarch64 self-hosted runner pool availability.