pyfg wheels are x86_64-only — please publish aarch64 (ARM64) builds, or open-source the FG library

#### Summary

`pyfg` is a hard dependency of TorchEasyRec, but every published wheel is
`linux_x86_64`-only. There is no `aarch64`/`arm64` build, no pure-Python
fallback and no sdist, so TorchEasyRec cannot be installed on any ARM64
Linux host. This blocks ARM-based training and offline feature-generation
workloads.

I would like to ask for either:

1. **aarch64 wheels** for the currently supported CPython versions, or
2. **open-sourcing the FG library** (source + build instructions) so the
community can build it for architectures you do not target.

Option 1 is the smaller ask and would unblock us immediately; option 2 is
the durable fix, since it also covers architectures beyond ARM.

Start by checking the published pyfg wheel metadata and the dependency path that prevents TorchEasyRec installation on ARM64 Linux. Done means either supported CPython aarch64 wheels are published or the FG library's source and build instructions are available; the issue names no repository files or tests to run.

Written by the indexing model from the issue text.