Add Linux ARM64 binary releases

[leocamello]

Summary

Support native Linux ARM64 (aarch64-unknown-linux-gnu) binary releases for home AI clusters running on ARM64 hardware.

Current State

• Linux ARM64 cross-compilation fails due to OpenSSL linking issues
• Docker images provide ARM64 support via QEMU emulation (slower builds, but works)
• Users on ARM64 can build from source or use Docker

Potential Solutions

1. Static linking with musl: Use aarch64-unknown-linux-musl target with rustls instead of OpenSSL
2. Cross-compilation sysroot: Set up proper ARM64 sysroot with OpenSSL headers
3. GitHub ARM64 runners: Use native ARM64 runners (limited availability)
4. Self-hosted runner: Set up ARM64 runner on home cluster

Workaround

# Docker (recommended for ARM64 users)
docker pull leocamello/nexus:latest

# Build from source on ARM64
cargo install nexus

Priority

Medium - Docker provides functional ARM64 support, but native binaries would be faster and more convenient.