Meta Proxy v0.7.1

Signed cross-platform binaries mirrored from cognitum-one/meta-proxy@v0.7.1. Verify SHA256SUMS.sig (raw Ed25519) against the key pinned in metaharness.

Fixes the GLIBC_2.39 floor (cognitum-one/meta-proxy#65). Linux binaries now build against a pinned glibc 2.28, so meta-proxy starts on Debian 10+/12, Ubuntu 22.04, and RHEL 9 / Amazon Linux 2023 — every published Linux binary through v0.7.0 died in the dynamic loader on those. Adds meta-proxy --version (#6).