Record Granite Speech 0.5.1 release

[benjipeng]

Summary

• record the successful mlx-speech 0.5.1 GitHub Actions and PyPI release
• record the public Granite Speech int8 Hugging Face revision, inventory, weight digest, and source blob matches
• record the isolated public PyPI + unauthenticated Hugging Face alias smoke test

Validation

• 914 passed in tests/unit/
• git diff --check passed
• PyPI metadata, Hugging Face repository metadata, remote LFS digest, README blob, and config blob were checked against their authoritative public endpoints